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![41
UNIT-I
( ) Method definition and invocation, defining precedence in
expressions, in control statements and type casting.
{ } Initializing arrays, define blocks of code for classes,
methods and local scopes.
[ ] Declare array types, dereference array types.
; Terminates statements.
, In variable declaration, in for statement.
. To separate package names from sub packages and
classes and to separate a variable or method from a
reference variable.
Separators
UNIT I 41](https://image.slidesharecdn.com/unit-inp-221021045702-e3a4a68c/85/Unit-INP-ppt-41-320.jpg)
![54
UNIT-I
Variables
Declaring a Variable:
In Java, all variables must be declared before they can be used.
type identifier [ =value][, identifier [=value] …];
UNIT I 54](https://image.slidesharecdn.com/unit-inp-221021045702-e3a4a68c/85/Unit-INP-ppt-54-320.jpg)
![62
UNIT-I
One-Dimensional Arrays:
The general form of a one-dimensional array declaration is:
type array-var[ ];
type[ ] array-var;
To allocate memory to an array new operator is used.
array-var=new type[size];
Ex:- int nums[ ]; int[ ] vals;
nums= new int[10]; vals=new int[20];
Array initializer will not use new operator.
Ex:- int days[ ]={ 1,2,3,4,5,6,7 };
UNIT I 62](https://image.slidesharecdn.com/unit-inp-221021045702-e3a4a68c/85/Unit-INP-ppt-62-320.jpg)
![63
UNIT-I
Multidimensional arrays are arrays of arrays.
Ex:- int twoDim1[ ][ ]=new int[4][5];
Multidimensional Arrays:
int twoDim2[ ][ ]=new int[4][ ];
twoDim2[0]=new int[1];
twoDim2[1]=new int[2];
twoDim2[2]=new int[3];
twoDim2[3]=new int[4];
UNIT I 63](https://image.slidesharecdn.com/unit-inp-221021045702-e3a4a68c/85/Unit-INP-ppt-63-320.jpg)
![70
UNIT-I
Operator Precedence:
( ) [ ] .
++ -- ~ !
* / %
+ -
>> >>> <<
> >= < <=
== !=
&
^
|
&&
||
?:
= Op=
High
Low
UNIT I 70](https://image.slidesharecdn.com/unit-inp-221021045702-e3a4a68c/85/Unit-INP-ppt-70-320.jpg)
![74
UNIT-I
Iteration statements:
while
do-while
for
In J2SE 5 a new version of for loop known as For-Each loop
was introduced.
Its general form is:
for( type itr-var : collection) statement-block
Collection is of any type of collection or array.
int nums[ ]={10,20,30,40,50};
int sum=0;
for(int x : nums) sum+=x;
UNIT I 74](https://image.slidesharecdn.com/unit-inp-221021045702-e3a4a68c/85/Unit-INP-ppt-74-320.jpg)
![100
UNIT-I
Constructors of String class:
String( )
String(char chars[ ])
String(char chars[ ], int startIndex, int numChars)
String(String strObj)
String(byte asciiChars[ ])
String(byte asciiChars[ ],int startIndex,int numChars)
String(StringBuffer strBufObj)
String(int codePoints[ ],int startIndex, int numChars) Added in J2SE 5
String(StringBuilder strBuildObj) Added in J2SE 5
UNIT I 100](https://image.slidesharecdn.com/unit-inp-221021045702-e3a4a68c/85/Unit-INP-ppt-100-320.jpg)
![104
UNIT-I
String Conversion and toString( ):
Java converts data into its string representation during concatenation by
calling one of the overloaded versions of the string conversion method
valueOf( ) defined by String class.
valueOf( ) is overloaded for all simple types and for type Object.
static String valueOf(int num)
static String valueOf(byte num)
static String valueOf(double num)
static String valueOf(long num)
static String valueOf(char chars[ ])
static String valueOf(Object ob)
static String valueOf(char chars[ ],int startIndex, int numChars)
UNIT I 104](https://image.slidesharecdn.com/unit-inp-221021045702-e3a4a68c/85/Unit-INP-ppt-104-320.jpg)
![106
UNIT-I
Example:
class Rect{
int length,breadth;
Rect(int x,int y) {
length=x;
breadth=y;
}
}
class Cube {
int length,width,height;
Cube(int x,int y,int z) {
length=x;
width=y;
height=z;
}
public String toString( ) {
return "Hai I am instance of Cube class";
}
}
class String1
{
public static void main(String args[])
{
Rect r1=new Rect(10,20);
String s1=“Rect:”+r1;
System.out.println(s1);
Cube b1=new Cube(10,20,30);
String s2=“Cube:”+b1;
System.out.println(s2);
}
}
O/P :
Rect:Rect@82ba41
Cube:Hai I am instance of Cube class
UNIT I 106](https://image.slidesharecdn.com/unit-inp-221021045702-e3a4a68c/85/Unit-INP-ppt-106-320.jpg)
![107
UNIT-I
Character Extraction:
String object cannot be indexed as if they were a character array.
Many of the String methods employ an index into the string for their operation
beginning at zero.
char charAt(int where)
void getChars(int sourceStart, int sourceEnd, char target[ ], int targetStart)
byte[ ] getBytes( )
char[ ] toCharArray( )
UNIT I 107](https://image.slidesharecdn.com/unit-inp-221021045702-e3a4a68c/85/Unit-INP-ppt-107-320.jpg)
![112
UNIT-I
Some other String Methods:
String replaceAll(String regExp,String newStr)
int codePointAt(int i) Added by J2SE 5
int codePointBefore(int i) “
int codePointCount(int start,int end) “
boolean contains(CharSequence str) “
boolean contentEquals(CharSequence str) “
boolean contentEquals(StringBuffer str)
static String format(String fmtstr,Object … args) “
static String format(Locale loc, String fmtstr, Object … args) “
boolean matches(String regExp)
int offsetByCodePoints(int start, int num) “
String replaceFirst(String regExp,String newStr)
String[ ] split(String regExp)
String[ ] split(String regExp, int max)
CharSequence subSequence(int startIndex, int stopIndex)
UNIT I 112](https://image.slidesharecdn.com/unit-inp-221021045702-e3a4a68c/85/Unit-INP-ppt-112-320.jpg)
![115
UNIT-I
Methods:
int length( ) string length
int capacity( ) total allocated capacity
void ensureCapacity(int capacity) preallocate
void setLength(int len)
char charAt(int where)
void setCharAt(int where, char ch)
void getChars(int sourceStart,int sourceEnd,char target[ ],int
targetStart)
Ensures that the capacity of the buffer is at least equal to the specified minimum.
The new capacity is the larger of:
a. The minimumCapacity argument.
b. Twice the old capacity, plus 2.
UNIT I 115](https://image.slidesharecdn.com/unit-inp-221021045702-e3a4a68c/85/Unit-INP-ppt-115-320.jpg)
![UNIT-I 121
Sample program: Single Inheritance
class A
{
int i,j;
void show( )
{
System.out.println(“i=”+i+” j=“+j);
}
}
class B extends A
{
int p,q;
void display( )
{
System.out.println(“p=“+p+” q=“+q);
}
void all( )
{
System.out.println(“i=”+i+” j=“+j+
“ p=“+p+” q=“+q);
}
}
class InheritanceDemo1
{
public static void main(String args[ ])
{
A obj1=new A( );
B obj2=new B( );
obj1.i=10;
obj1.j=20;
obj2.i=30;
obj2.j=40;
obj2.p=50;
obj2.q=60;
obj1.show( );
obj2.display( );
obj2.all( );
obj2.show( );
}
} O/P:
i=10 j=20
p=50 q=60
i=30 j=40 p=50 q=60
i=30 j=40
UNIT I](https://image.slidesharecdn.com/unit-inp-221021045702-e3a4a68c/85/Unit-INP-ppt-121-320.jpg)
![UNIT-I 123
Sample program: Use of private keyword
class A
{
private int i,j;
void show( )
{
System.out.println(“i=”+i+” j=“+j);
}
}
class B extends A
{
int p,q;
void display( )
{
System.out.println(“p=“+p+” q=“+q);
}
void all( )
{
System.out.println(“i=”+i+” j=“+j+
“ p=“+p+” q=“+q);
}
}
class InheritanceDemo2
{
public static void main(String args[ ])
{
A obj1=new A( );
B obj2=new B( );
obj1.i=10;
obj1.j=20;
obj2.i=30;
obj2.j=40;
obj2.p=50;
obj2.q=60;
obj1.show( );
obj2.display( );
obj2.all( );
obj2.show( );
}
}
Compile time ERROR
UNIT I 123](https://image.slidesharecdn.com/unit-inp-221021045702-e3a4a68c/85/Unit-INP-ppt-123-320.jpg)
![UNIT-I 125
Sample program: Superclass variable referencing a subclass object
class A
{
int i,j;
void show( )
{
System.out.println(“i=”+i+” j=“+j);
}
}
class B extends A
{
int p,q;
void display( )
{
System.out.println(“p=“+p+” q=“+q);
}
void all( )
{
System.out.println(“i=”+i+” j=“+j+
“ p=“+p+” q=“+q);
}
}
class InheritanceDemo3
{
public static void main(String args[ ])
{
A obj1=new A( );
B obj2=new B( );
obj1.i=10;
obj1.j=20;
obj2.i=30;
obj2.j=40;
obj2.p=50;
obj2.q=60;
obj1.show( );
obj1=obj2;
obj1.show( );
}
}
O/P:
i=10 j=20
i=30 j=40
UNIT I](https://image.slidesharecdn.com/unit-inp-221021045702-e3a4a68c/85/Unit-INP-ppt-125-320.jpg)
![128
class A{
int i, j;
A( ){
System.out.println(“A default”);
}
A(int a, int b){
i=a;
j=b;
System.out.println(“A with 2 args”);
}
void show( ){
System.out.println(“i=”+i+” j=“+j);
}}
class B extends A{
int p,q;
B( ){
System.out.println(“B default”);
}
B(int a, int b, int c, int d){
super(a,b);
p=c;
q=d;
Sample program: super(parameter-list)
System.out.println(“B with 4 args”);
}
void all( ){
System.out.println(“i=”+i+” j=“+j+“ p=“+p+”
q=“+q);
}}
class SuperConstructor{
public static void main(String args[ ]){
A obj1=new A( );
B obj2=new B(30,40,50,60);
obj1.show( );
obj2.all( );
obj2.show( );
}}
O/P:
A default
A with 2 args
B with 4 args
i=0 j=0
i=30 j=40 p=50 q=60
i=30 j=40
UNIT I](https://image.slidesharecdn.com/unit-inp-221021045702-e3a4a68c/85/Unit-INP-ppt-128-320.jpg)
![130
class A{
int i, j;
A( ){
System.out.println(“A default”);
}
A(int a, int b){
i=a;
j=b;
System.out.println(“A with 2 args”);
}
void show( ){
System.out.println(“i=”+i+” j=“+j);
}}
class B extends A{
int i, j, p, q;
B( ){
System.out.println(“B default”);
}
B(int a, int b, int c, int d){
super(a,b);
i=c;
j=d;
Sample program: super.member
System.out.println(“B with 4 args”);
}
void all( ){
System.out.println(“Ai=”+super.i+”Aj=“+
super.j+“ i=“+i+” j=“+j);
}}
class SuperMember{
public static void main(String args[ ]){
A obj1=new A( );
B obj2=new B(30,40,50,60);
obj1.show( );
obj2.all( );
obj2.show( );
}}
O/P:
A default
A with 2 args
B with 4 args
i=0 j=0
Ai=30 Aj=40 i=50 j=60
i=30 j=40 130](https://image.slidesharecdn.com/unit-inp-221021045702-e3a4a68c/85/Unit-INP-ppt-130-320.jpg)
![UNIT-I 132
class A
{
int i,j;
A( )
{
System.out.println("A default");
}
}
class B extends A
{
int p,q;
B( )
{
System.out.println("B default");
}
}
Sample Program: Multilevel Inheritance
O/P: ?
class C extends B
{
int x,y;
C( )
{
System.out.println("C default");
}
}
class ConstructorOrder1
{
public static void main(String args[ ])
{
C c1=new C();
}
}
UNIT I 132](https://image.slidesharecdn.com/unit-inp-221021045702-e3a4a68c/85/Unit-INP-ppt-132-320.jpg)
![UNIT-I 134
class C extends B {
int x,y;
C( ) {
System.out.println("C default");
}
C(int a,int b,int c,int d,int e,int f) {
super(a,b,c,d);
x=e;
y=f;
System.out.println("C 6 args");
}
void display( ) {
System.out.println("i="+i+"j="+j+"p="+p+"q="+
q+"x="+x+"y="+y);
}}
class ConstructorOrder2 {
public static void main(String args[]) {
C c1=new C(10,20,30,40,50,60);
c1.display();
}}
class A{
int i,j;
A( ) {
System.out.println("A default");
}
A(int a, int b) {
i=a;
j=b;
System.out.println("A 2 args");
}}
class B extends A {
int p,q;
B( ) {
System.out.println("B default");
}
B(int a,int b,int c,int d) {
super(a,b);
p=c;
q=d;
System.out.println("B 4 args");
}}
Sample Program: Multilevel Inheritance
UNIT I 134](https://image.slidesharecdn.com/unit-inp-221021045702-e3a4a68c/85/Unit-INP-ppt-134-320.jpg)
![UNIT-I 137
class A{
int i, j;
void show( ){
System.out.println(“This is in A’s show “);
}}
class B extends A{
int p, q;
void show( ){
super.show( );
System.out.println(“This is in B’s show “);
}}
class Override{
public static void main(String args[ ]){
A obj1=new A( );
B obj2=new B( );
obj1.show( );
obj2.show( );
}}
Sample program: Method Overriding
O/P:
This is in A’s show
This is in A’s show
This is in B’s show
UNIT I 137](https://image.slidesharecdn.com/unit-inp-221021045702-e3a4a68c/85/Unit-INP-ppt-137-320.jpg)
![UNIT-I 139
class A {
void callme( ) {
System.out.println("A's method");
}
}
class B extends A {
void callme( ) {
System.out.println("B's method");
}
}
class C extends A {
void callme( ) {
System.out.println("C's method");
}
}
class DynamicMethodDispatch {
public static void main(String args[]) {
A a1=new A( );
B b1=new B( );
C c1=new C( );
A p1;
p1=a1;
p1.callme( );
p1=b1;
p1.callme( );
p1=c1;
p1.callme();
}
}
Sample program: Dynamic Method Dispatch
O/P:-
A’s method
B’s method
C’s method
UNIT I 139](https://image.slidesharecdn.com/unit-inp-221021045702-e3a4a68c/85/Unit-INP-ppt-139-320.jpg)
![UNIT-I 141
abstract class A
{
void show( )
{
System.out.println("A's show method");
}
abstract void display(int x,int y);
}
class B extends A
{
void m1( )
{
System.out.println("Method m1");
}
void display(int x, int y)
{
System.out.println("Param1="+x+
" Param2="+y);
}
}
Sample program1: Abstract classes
O/P:-
Param1=10 Param2=20
class AbstractClass
{
public static void main(String args[ ])
{
B b1=new B();
b1.display(10,20);
}
}
UNIT I 141](https://image.slidesharecdn.com/unit-inp-221021045702-e3a4a68c/85/Unit-INP-ppt-141-320.jpg)
![UNIT-I 142
Sample program2: Abstract classes
class AbstractClass2
{
public static void main(String args[ ])
{
B b1=new B( );
b1.display(10,20);
A a1;
a1=b1;
a1.display(30,40);
}
}
O/P:-
Param1=10 Param2=20
Param1=30 Param2=40
abstract class A
{
void show( )
{
System.out.println("A's show method");
}
abstract void display(int x,int y);
}
class B extends A
{
void m1( )
{
System.out.println("Method m1");
}
void display(int x, int y)
{
System.out.println("Param1="+x+
" Param2="+y);
}
} UNIT I 142](https://image.slidesharecdn.com/unit-inp-221021045702-e3a4a68c/85/Unit-INP-ppt-142-320.jpg)
Uploaded byOsmania University
Unit-INP.ppt
This document provides an overview of key concepts in Java programming including object-oriented principles like encapsulation, inheritance and polymorphism. It discusses Java characteristics such as being simple, object-oriented, architecture neutral and portable. It also covers Java history, compilers, data types, variables, operators, control flow statements, arrays, methods and other core Java topics. The document is intended as teaching material for an introductory Java programming course.
More Related Content
Unit-INP.ppt
- 1. 1 UNIT-I Java Programming II B.TechI-Sem CSE Unit-I By, Namita Parati UNIT I 1
- 2.
- 3. 3 UNIT-I Data abstraction Encapsulation Inheritance Benefits ofinheritance Polymorphism Classes and objects Procedural and OOP paradigms History of Java Java buzzwords Comments Data types, variables, constants Scope and life time of variables Operators, operator hierarchy Expressions Type conversion and casting Enumerated types Control flow, block scope Conditional statements Loops Break and continue statements Simple java program Arrays Input and output, formatting output Constructors Methods, parameter passing static fields and methods Access control this reference Overloading methods Overloading constructors Recursion Garbage collection Building strings Exploring string class Contents: UNIT I 3
- 4. UNIT-I 4 Contents Inheritance: Definition, typesof Inheritance Member Access rules Superclass and subclass super keyword final keyword Base class Object Polymorphism: Method overriding Dynamic Method Dispatch Abstract classes and methods UNIT I 4
- 5.
- 6. 6 UNIT-I Encapsulation is themechanism that binds together code and the data it manipulates. In Java, the basis of encapsulation is the class. A class defines the structure and behavior that will be shared by a set of objects. The data defined by the class are referred to as member variables or instance variables. The code that operates on that data is referred to as member methods or just methods. OOP Principles Encapsulation: Inheritance: Polymorphism: UNIT I 6
- 7. 7 UNIT-I Inheritance is theprocess by which one object acquires the properties of another object. OOP Principles Encapsulation: Inheritance: Polymorphism: UNIT I 7
- 8. 8 UNIT-I Polymorphism is afeature that allows one interface to be used for a general class of actions. The specific action is determined by the exact nature of the situation. OOP Principles Encapsulation: Inheritance: Polymorphism: UNIT I 8
- 9. UNIT I Forms ofInheritance: Inheritance for Specialization: The child is special case of the parent class. Inheritance for Specification: The parent class defines behavior that is implemented in the child class but not in the parent class. Inheritance for Construction: The child class makes use of the behavior provided by the parent class but is not a subtype of the parent class. Inheritance for Extension: The child class adds new functionality to the parent class, but does not change any inherited behavior. Inheritance for Limitation: The child class restricts the use of some of the behavior inherited from the parent class. Inheritance for Combination: The child class inherits features from more than one parent class. 9 UNIT-I 9
- 10. UNIT I Benefits ofInheritance: Some of the important benefits of inheritance: Software Reusability Increased Reliability Code Sharing Consistency of Interface Software Components Rapid Prototyping Polymorphism and Frameworks Information Hiding 10 UNIT-I 10
- 11.
- 12. 12 UNIT-I Computer programs, knownas software, are instructions to the computer. Without programs, a computer is an empty machine. Computers do not understand human languages, so we need to use computer languages to communicate with them. Programs are written using programming languages. Programs UNIT I 12
- 13. 13 UNIT-I Programming Languages Machine Language: Assembly Language : High-Level Language : UNIT I 13
- 14. 14 UNIT-I Programming Languages High-Level Language: COBOL (COmmon Business Oriented Language) FORTRAN (FORmula TRANslation) BASIC (Beginner All-purpose Symbolic Instructional Code) Pascal (named for Blaise Pascal) Ada (named for Ada Lovelace) C (whose developer designed B first) Visual Basic (Basic-like visual language developed by Microsoft) Delphi (Pascal-like visual language developed by Borland) C++ (an object-oriented language, based on C) Java (We use it in the book) UNIT I 14
- 15. 15 UNIT-I Compiling Source Code Aprogram written in a high-level language is called a source program. Since a computer cannot understand a source program. Program called a compiler is used to translate the source program into a machine language program called an object program. The object program is often then linked with other supporting library code before the object can be executed on the machine. Compiler Source File Object File Linker Excutable File UNIT I 15
- 16.
- 17. 17 UNIT-I Java’s History • Javawas conceived by James Gosling at Sun Microsystems in 1991. • It took 18 months to develop the first working version. • This language was initially called “Oak”, but was renamed “Java” in 1995. • Java is the name of the island in Indonesia. • The Java coffee is from the Java island. • The name was chosen during one of several brainstorming sessions held by the Java software team. • "Java" was chosen from among many, many suggestions. • The name is not an acronym, but rather a reminder of that hot, aromatic stuff that many programmers like to drink lots of UNIT I 17
- 18.
- 19. 19 UNIT-I JDK Versions JDK 1.0(January 21, 1996) JDK 1.1 (February 19, 1997) J2SE 1.2 (December 8, 1998) J2SE 1.3 (May 8, 2000) J2SE 1.4 (February 6, 2002) J2SE 5.0 (September 30, 2004) Java SE 6 (December 11, 2006) Java SE 7 (July 28, 2011) Java SE 8 (March 18, 2014) UNIT I 19
- 20. 20 UNIT-I JDK Editions • JavaStandard Edition (J2SE) • J2SE can be used to develop client-side standalone applications or applets. • Java Enterprise Edition (J2EE) • J2EE can be used to develop server-side applications such as Java servlets and Java ServerPages. • Java Micro Edition (J2ME). • J2ME can be used to develop applications for mobile devices such as cell phones. UNIT I 20
- 21. 21 UNIT-I Compiling Java SourceCode •Java was designed to run object programs on any platform. •With Java, you write the program once, and compile the source program into a special type of object code, known as bytecode. •The bytecode can then run on any computer with a Java Virtual Machine. •Java Virtual Machine is a software that interprets Java bytecode. Java Bytecode Java Virtual Machine Any Computer UNIT I 21
- 22. 22 UNIT-I Java is Compiledand Interpreted Text Editor Compiler Interpreter Programmer Source Code .java file Byte Code .class file Hardware and Operating System Notepad, editplus, Edit etc javac java appletviewer netscape UNIT I 22
- 23. 23 UNIT-I 23 Java Translation andExecution Java source code Java compiler Java interpreter for Windows Java interpreter for Razr v2 Java bytecode Java interpreter for Mac Java interpreter for Linux UNIT I 23
- 24.
- 25. 25 UNIT-I Characteristics of Java •Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic UNIT I 25
- 26. 26 UNIT-I Characteristics of Java •Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic Because Java inherits C/C++ syntax and many of the object- oriented features of C++, learning Java will be easier. UNIT I 26
- 27. 27 UNIT-I Characteristics of Java •Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic Java is inherently object-oriented. Although many object-oriented languages began strictly as procedural languages, Java was designed from the start to be object-oriented. Object-oriented programming (OOP) is a popular programming approach that is replacing traditional procedural programming techniques. One of the central issues in software development is how to reuse code. Object- oriented programming provides great flexibility, modularity, clarity, and reusability through encapsulation, inheritance, and polymorphism. UNIT I 27
- 28. 28 UNIT-I Characteristics of Java •Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic Distributed computing involves several computers working together on a network. Java is designed to make distributed computing easy. Java also supports Remote Method Invocation (RMI). UNIT I 28
- 29. 29 UNIT-I Characteristics of Java •Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic Java enables the creation of cross- platform programs by compiling into an intermediate representation called Java bytecode. This code can be executed on any system that implements the Java Virtual Machine UNIT I 29
- 30. 30 UNIT-I Characteristics of Java •Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic Java compilers can detect many problems that would first show up at execution time in other languages. Java has eliminated certain types of error-prone programming constructs found in other languages. Java has a runtime exception-handling feature to provide programming support for robustness. UNIT I 30
- 31. 31 UNIT-I Characteristics of Java •Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic By using a Java-compatible web browser, we can safely download Java applets without fear of viral infection or malicious intent. Java achieves this protection by confining a Java program to the Java execution environment and not allowing it access to other parts of the computer. UNIT I 31
- 32. 32 UNIT-I Characteristics of Java •Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic Write once, run anywhere With a Java Virtual Machine (JVM), you can write one program that will run on any platform. UNIT I 32
- 33. 33 UNIT-I Characteristics of Java •Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic Because Java is architecture neutral, Java programs are portable. They can be run on any platform without being recompiled. UNIT I 33
- 34. 34 UNIT-I Characteristics of Java •Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic The Just-in-time compilers allow the platform-independent Java programs to be executed with nearly the same run- time performance as conventional compiled programs UNIT I 34
- 35. 35 UNIT-I Characteristics of Java •Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic Multithread programming is smoothly integrated in Java, which allows you to write programs that do many things simultaneously. Whereas in other languages you have to call procedures specific to the operating system to enable multithreading. UNIT I 35
- 36. 36 UNIT-I Characteristics of Java •Java Is Simple • Java Is Object-Oriented • Java Is Distributed • Java Is Interpreted • Java Is Robust • Java Is Secure • Java Is Architecture-Neutral • Java Is Portable • Java's Performance • Java Is Multithreaded • Java Is Dynamic Java programs carry with them substantial amounts of run-time type information that is used to verify and resolve accesses to objects at run time. This makes it possible to dynamically link code in a safe and expedient manner. UNIT I 36
- 37.
- 38. 38 UNIT-I Three types ofcomments • Single-line // • Multi-line /* */ • Documentation comment /** */ This type of comment is used to produce an HTML file that documents your program. Comments UNIT I 38
- 39. 39 UNIT-I Naming Conventions • Variablesand method names: • Use lowercase. If the name consists of several words, concatenate all in one, use lowercase for the first word, and capitalize the first letter of each subsequent word in the name. For example:- radius, area, computeArea. • Class names: • Capitalize the first letter of each word in the name. Example:- FirstProgram, Sample, DemoBoxWeight. • Constants: • Capitalize all letters in constants, and use underscores to connect words. Example:- PI, MAX_VALUE. UNIT I 39
- 40. 40 UNIT-I Identifiers • An identifieris a sequence of characters that consist of uppercase and lowercase letters, digits, underscores ( _ ), and dollar signs ($). • An identifier must start with a letter, an underscore (_), or a dollar sign ($). It cannot start with a digit. • An identifier cannot be a reserved word. • An identifier cannot be true, false, or null. • An identifier can be of any length. UNIT I 40
- 41. 41 UNIT-I ( ) Methoddefinition and invocation, defining precedence in expressions, in control statements and type casting. { } Initializing arrays, define blocks of code for classes, methods and local scopes. [ ] Declare array types, dereference array types. ; Terminates statements. , In variable declaration, in for statement. . To separate package names from sub packages and classes and to separate a variable or method from a reference variable. Separators UNIT I 41
- 42. 42 UNIT-I enum Keywords are reservedwords recognized by Java that cannot be used as identifiers. Java defines 50 keywords as follows: Keywords UNIT I 42
- 43. 43 UNIT-I Data Types Java defineseight primitive data types: byte, short, int, long, char, float, double and boolean. These are put into four groups: → Integers → Floating-point numbers → Characters → Boolean UNIT I 43
- 44. 44 UNIT-I Integers: Name Width Range long64 -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 int 32 -2,147,483,648 to 2,147,483,647 short 16 -32,768 to 32,767 byte 8 -128 to 127 UNIT I 44
- 45. 45 UNIT-I Name Width Range double64 4.9e-324 to 1.8e+308 float 32 1.4e-045 to 3.4e+038 Floating-Point Types: UNIT I 45
- 46. 46 UNIT-I Characters: ► In Java,the data type used to store characters is char. ► Java uses Unicode to represent characters. ► Unicode defines a fully international character set that can represent all of the characters found in all human languages. Such as Latin, Greek, Arabic, Cyrillic, Hebrew, Katakana, Hangul and many more. ► For this purpose char is 16 bits width. ► The range of char is 65,536. ► The standard set of characters known as ASCII in Unicode ranges from 0 to 255. UNIT I 46
- 47. 47 UNIT-I Booleans: ► Java hasa primitive type called boolean for logical values. ► It can have only one of two possible values, true or false. ► It requires one bit. ► When a boolean value is output by println( ), “true” or “false is displayed. ► If b is boolean variable, then there is no need to write an if statement like this: if(b==true) … ► The outcome of a relational operator is boolean value. UNIT I 47
- 48. 48 UNIT-I Literals Integer Literals: ► Integerliterals can be represented using any of the three bases decimal, octal, hexadecimal and binary(Java SE 7). ► Any whole number is a decimal(base 10) number. ► Octal(base 8) values are denoted in Java by a leading zero. Ex: 05, 012,0734 ► Hexadecimal(base 16) values are denoted in Java by a leading zero-x(0x or0X). Digits is 0 to 9, A to F (a to f). Ex: 0x12, 0X45, 0X1B ► Binary(base 2) values are denoted in by a leading 0b or0B. Ex: 0b1011, 0B11011 UNIT I 48
- 49. 49 UNIT-I Integer Literals: ► FromJava SE 7 underscore can be used in integer literals. Ex: int a=25_37 which is equivalent to a=2537 ► Integer literals create a int value which is a 32-bit integer value and can be assigned even to byte and short if it is in the range. ► Integer literals can also be used for long, however we can specify long literals explicitly by appending an upper or lower case L to integer literal. Ex: 1234L,0x52dfL UNIT I 49
- 50. 50 UNIT-I Floating-Point Literals: ► Floating-pointnumbers represent decimal values with a fractional component. They can be expressed in either standard or scientific notation. Standard notation: 2.34, 3.14159 Scientific notation: 6.022E23, 314159e-5 ► Floating-point literals in Java default to double precision. ► To specify a float literal, append an F or f to the constant. Ex:- 24.89f, 10076.45F ► double literal can also be specified explicitly by appending a D or d. Ex:- 24.89, 24.89d, 12.0056D UNIT I 50
- 51. 51 UNIT-I Boolean Literals: ► Thereare only two logical values that boolean can have, true and false. ► The true literal in Java does not equal 1 nor does the false literal equal 0. UNIT I 51
- 52. 52 UNIT-I Character Literals: A characterliteral is represented inside a pair of single quotes. All of the visible ASCII characters can be directly entered inside the quotes, such as ‘a’, ‘z’, ‘@’. For characters that are impossible to enter directly, there are several escape sequences to enter the character. UNIT I 52
- 53. 53 UNIT-I Escape Sequence Description dddOctal character (ddd) uxxxx Hexadecimal Unicode character(xxxx) ’ Single quote ” Double quote Blackslash r Carriage return n New line f Form feed t Tab b Backspace Character Escape Sequence UNIT I 53
- 54. 54 UNIT-I Variables Declaring a Variable: InJava, all variables must be declared before they can be used. type identifier [ =value][, identifier [=value] …]; UNIT I 54
- 55. 55 UNIT-I The Scope andLifetime of Variables ► A scope determines what objects are visible to other parts of your program. ► It also determines the lifetime of those objects. ► In Java, the two major scopes are those defined by a class and those defined by a method. UNIT I 55
- 56.
- 57. 57 UNIT-I Type Conversion andCasting Java supports both automatic type conversion and casting. Java’s Automatic Conversions: When one type of data is assigned to another type of variable, an automatic type conversion will take place if the following two conditions are met: • The two types are compatible. • The destination type is larger than the source type. When these two conditions are met, a widening conversion takes place. Ex:- int to long, byte to int, float to double … UNIT I 57
- 58. 58 UNIT-I To create aconversion between two incompatible types use a cast. A cast is an explicit type conversion. The general form is: (target-type) value This type of conversion is some times called a narrowing conversion. A different type of conversion will occur when a floating-point value is assigned to an integer type: truncation. b=(byte)i; i=(int)d; Casting Incompatible Types: Ex:- int i=257; byte b; double d=456.132; UNIT I 58
- 59. 59 UNIT-I Java automatically promoteseach byte or short operand to int when evaluating an expression. Ex:- byte a=5, b=10; a=a*b; //error int c=a*b; a=(byte)(a*b); Automatic Type Promotion in Expressions: In addition to the above, Java automatic type promotion rules are: 1. If one of the operands is double, the whole expression is promoted to double. 2. Otherwise, if one of the operands is float, the whole expression is promoted to float. 3. Otherwise, if one of the operands is long, the whole expression is promoted to long. UNIT I 59
- 60.
- 61. 61 UNIT-I Arrays An array isa group of like-typed variables that are referred to by a common name. One-Dimensional Arrays Multidimensional Arrays UNIT I 61
- 62. 62 UNIT-I One-Dimensional Arrays: The generalform of a one-dimensional array declaration is: type array-var[ ]; type[ ] array-var; To allocate memory to an array new operator is used. array-var=new type[size]; Ex:- int nums[ ]; int[ ] vals; nums= new int[10]; vals=new int[20]; Array initializer will not use new operator. Ex:- int days[ ]={ 1,2,3,4,5,6,7 }; UNIT I 62
- 63. 63 UNIT-I Multidimensional arrays arearrays of arrays. Ex:- int twoDim1[ ][ ]=new int[4][5]; Multidimensional Arrays: int twoDim2[ ][ ]=new int[4][ ]; twoDim2[0]=new int[1]; twoDim2[1]=new int[2]; twoDim2[2]=new int[3]; twoDim2[3]=new int[4]; UNIT I 63
- 64.
- 65. 65 UNIT-I Operators Arithmetic Operators Bitwise Operators RelationalOperators Boolean Logical Operators UNIT I 65
- 66. 66 UNIT-I The operands ofthe arithmetic operators must be of a numeric type. These can also be used on char types. Operator Description + Addition - Subtraction * Multiplication / Division % Modulus ++ Increment -- Decrement += Addition assignment -= Subtraction assignment *= Multiplication assignment /= Division assignment %= Modulus assignment Arithmetic Operators: UNIT I 66
- 67. 67 UNIT-I Java defines severalbitwise operators which can be applied to the types, long, int, short, char and byte. These operators act upon the individual bits of their operands. Operator Description ~ Bitwise unary NOT & Bitwise AND | Bitwise OR ^ Bitwise exclisive OR >> Shift right >>> Shift right zero fill << Shift left &= Bitwise AND assignment |= Bitwise OR assignment ^= Bitwise exclisive OR assignment >>= Shift right assignment >>>= Shift right zero fill assignment <<= Shift left assignment Bitwise Operators: UNIT I 67
- 68. 68 UNIT-I The relational operatorsdetermine the relationship that one operand has to the other. The outcome of these operations is a boolean value. Operator Description == Equal to != Not equal to > Greater than < Less than >= Greater than or equal to <= Less than or equal to Relational Operators: UNIT I 68
- 69. 69 UNIT-I These operators operateonly on boolean operands and result a boolean value. Operator Description & Logical AND | Logical OR ^ Logical XOR || Short-circuit OR && Short-circuit AND ! Logical unary NOT &= AND assignment |= OR assignment ^= XOR assignment == Equal to != Not equal to ?: Ternary if-then-else Boolean Logical Operators: UNIT I 69
- 70. 70 UNIT-I Operator Precedence: ( )[ ] . ++ -- ~ ! * / % + - >> >>> << > >= < <= == != & ^ | && || ?: = Op= High Low UNIT I 70
- 71.
- 72. 72 UNIT-I Control Statements Java’s controlstatements are put into three categories: • Selection statements: if and switch. • Iteration statements: for, while and do-while. • Jump statements: break, continue and return. UNIT I 72
- 73. 73 UNIT-I Selection statements: if if-else Nested ifs Theif-else-if ladder switch Nested switch Statements. UNIT I 73
- 74. 74 UNIT-I Iteration statements: while do-while for In J2SE5 a new version of for loop known as For-Each loop was introduced. Its general form is: for( type itr-var : collection) statement-block Collection is of any type of collection or array. int nums[ ]={10,20,30,40,50}; int sum=0; for(int x : nums) sum+=x; UNIT I 74
- 75. 75 UNIT-I Jump Statements: break: In java,the break statement has three uses, • In a switch statement. • To exit a loop. • Can be used as a form of goto. The general form of the third type of break is: break label; Label is the name of a label that identifies a block of code. When this form of break executes control is transferred out of the named block of code. Java label is a valid identifier followed by a colon. UNIT I 75
- 76. 76 UNIT-I continue: Used in loops. Alsoused with label. The general form of continue with label is: continue label; return: The return statement is used to explicitly return from a method. UNIT I 76
- 77.
- 78. 78 UNIT-I Class Fundamentals • Aclass defines a new data type. • Once defined can be used to create objects of that type. • A class is a template for an object. • An object is an instance of a class. UNIT I 78
- 79. 79 UNIT-I The general formof a class definition is: class classname { type instance-variable1; type instance-variable2; // . . . type instance-variableN; type methodname1(parameter-list){ // body of method } type methodname2(parameter-list){ // body of method } // . . . type methodnameM(parameter-list){ // body of method } } UNIT I 79
- 80. 80 UNIT-I • The data(or) variables defined within a class are called instance variables because each instance (object) of the class contains its own copy of these variables. • The code is contained within methods. • Collectively, the methods and variables defined within a class are called members of the class. Class Fundamentals UNIT I 80
- 81. 81 UNIT-I Declaring Objects: The objectis defined in two-steps: 1. Declare a variable of the class type. classname class-var; 2. Acquire an actual, physical copy of the object and assign it to that variable using a new operator. class-var=new classname( ); Box mybox; mybox=new Box( ); null mybox mybox width height depth Ex:- class Box { double width; double height; double depth; } UNIT I 81
- 82. 82 UNIT-I Assigning Object ReferenceVariables: Box b1=new Box(); Box b2; b2=b1; After these above statements both b1 b2 refer to the same object. In the first statement object b1 is created and memory is allocated to it. After the 3rd statement b2 refers to the same object as b1 refer to. Any changes made to object through b2 will affect to b1. width height depth b1 b2 Box object null UNIT I 82
- 83.
- 84. 84 UNIT-I Constructors: • A constructorinitializes an object immediately upon creation. • It has the same name as the class in which it resides. • Similar to a method but does not have a return type. • Automatically called immediately after the object creation, before new operator completes. • The constructor’s job is to initialize the internal state of an object. • Constructors can be with no parameters (default) as well as with parameters. Box(double w, double h, double d) { width=w; height=h; depth=d; } Ex:- Box( ) { width=10; height=20; depth=30; } Box b1=new Box( ); Box b2=new Box(40,50,60); UNIT I 84
- 85.
- 86. 86 UNIT-I Methods: The general formof a method: type name(parameter-list){ // body of method } Overloading Methods: • In a class, if two or more methods are defined with the same name and different parameter declarations, then the methods are said to be overloaded and the process is referred to as method overloading. • Method overloading is one of the ways that Java supports polymorphism. • Variable-Length Arguments UNIT I 86
- 87. 87 UNIT-I Variable-Length Arguments(Varargs): A methodthat takes a variable number of arguments is called a variable-arity method (or) a varargs method. A variable length argument is specified by three periods (…). Ex:- void add(int … v) A method can have normal parameters along with a variable-length parameter. The variable-length parameter must be the last parameter declared by the method. Ex:- void display(int a, int … p) void test(boolean a, boolean b, double c, char … d) There must be only one variable-length parameter UNIT I 87
- 88. 88 UNIT-I Overloading Varargs Methods: Varargsmethods can be overloaded in two ways: 1) The types of vararg parameter can differ. 2) To add a normal parameter. UNIT I 88
- 89. 89 UNIT-I Varargs and Ambiguity: voiddisplay(int ... a) { System.out.print("Parameters:"); for(int x:a) System.out.print(" "+x); System.out.println(); } void display(char ... ch) { System.out.print("Parameters:"); for(char x:ch) System.out.print(" "+x); System.out.println(); } s1.display( ); void display(int a, int ... v) { System.out.print("Parameters:"+a); for(int x:v) System.out.print(" "+x); System.out.println(); } void display(int ... w) { System.out.print("Parameters2:"); for(int x:w) System.out.print(" "+x); System.out.println(); } s1.display(10); UNIT I 89
- 90.
- 91. 91 UNIT-I The this Keyword: ‘this’keyword can be used inside any method to refer to the current object. class Rect { int length,breadth; void init(int a, int b){ length=a; breadth=b; } } Rect r1=new Rect( ); r1.init(10,20); class Rect { int length,breadth; void init(int length, int breadth){ length=length; breadth=breadth; } } Rect r1=new Rect( ); r1.init(10,20); class Rect { int length,breadth; void init(int length, int breadth){ this.length=length; this.breadth=breadth; } } Rect r1=new Rect( ); r1.init(10,20); UNIT I 91
- 92. 92 UNIT-I static keyword: Normally, aclass member must be accessed only with an object of its class. It is possible to create a member that can be accessed before any objects of its class are created and without reference to an object. To create such a member, precede its declaration with the keyword static. Such members can be accessed with the class name by the dot operator. class Sample { static int a=10; static int b; static void methodOne(int p, int q) { System.out.println(“p=“+p+”q=“+q); } } int c=Sample.a+Sample.b; Sample.methodOne(5,6); UNIT I 92
- 93. 93 UNIT-I All instances ofthe class share the same static variable. static variables: Instance variables declared as static are essentially global variables. When objects of a class are declared, no copy of a static variable is made. To initialize static variables, declare a static block which get executed exactly once, when the class is first loaded. UNIT I 93
- 94. 94 UNIT-I Methods declared asstatic have several restrictions: • They can only call other static methods. • They must only access static data. • They cannot refer to this and super in any way. static methods: UNIT I 94
- 95. 95 UNIT-I final keyword: final canbe applied for variables, methods and classes. final variable contents cannot be modified. final variable must be initialized when it is declared. Variables declared as final do not occupy memory on a per-instance basis. A final variable is a constant. Ex:- final int FILE_NEW=1; final int FILE_OPEN=2; UNIT I 95
- 96.
- 97. 97 UNIT-I Garbage Collection: In java,objects are dynamically allocated by using the new operator. Such objects are automatically destroyed and their memory is released when no references to the objects exists. The technique that accomplishes this is called garbage collection. Sometimes an object will need to perform some action when it is destroyed. Java provides a mechanism called finalization using which we can define specific actions that will occur when an object is just about to be reclaimed by the garbage collector. To add a finalizer to a class, simply define the finalize() method, which the Java runtime calls this method whenever it is about to recycle an object. protected void finalize( ) { // finalization code } UNIT I 97
- 98.
- 99. 99 UNIT-I Strings in Java: Astring is a sequence of characters. Java implements strings as objects of type String class. When a String object is created, a string is created that cannot be changed. We can still perform all types of string operations, but each time an existing string is altered a new String object is created that contains the modifications. Java provide two classes to create modifiable strings. They are StringBuffer and StringBuilder. The classes String, StringBuffer and StringBuilder are defined in java.lang package. All are final. UNIT I 99
- 100. 100 UNIT-I Constructors of Stringclass: String( ) String(char chars[ ]) String(char chars[ ], int startIndex, int numChars) String(String strObj) String(byte asciiChars[ ]) String(byte asciiChars[ ],int startIndex,int numChars) String(StringBuffer strBufObj) String(int codePoints[ ],int startIndex, int numChars) Added in J2SE 5 String(StringBuilder strBuildObj) Added in J2SE 5 UNIT I 100
- 101. 101 UNIT-I String Literals: String s= ”abcdefghij”; String Length: int length( ) UNIT I 101
- 102. 102 UNIT-I String Concatenation: The +operator concatenates two strings, producing a String object as the result. Example1: String age = “9”; String s = “He is “ + age + “ years old. “; System.out.println( s ); The O/P here is “He is 9 years old.” Example2: int age = 9; String s = “He is “ + age + “ years old. “; System.out.println( s ); The O/P here is also “He is 9 years old.” UNIT I 102
- 103. 103 UNIT-I Example3: String s =“abcdefghij “ + 20 + 30; System.out.println( s ); The O/P here is “abcdefghij 2030” String Concatenation: This is because the compiler automatically converts an operand to its string equivalent whenever the other operand of the + operator is an instance of String. Example4: String s = “abcdefghij “ + (20 + 30); System.out.println( s ); The O/P here is “abcdefghij 50” UNIT I 103
- 104. 104 UNIT-I String Conversion andtoString( ): Java converts data into its string representation during concatenation by calling one of the overloaded versions of the string conversion method valueOf( ) defined by String class. valueOf( ) is overloaded for all simple types and for type Object. static String valueOf(int num) static String valueOf(byte num) static String valueOf(double num) static String valueOf(long num) static String valueOf(char chars[ ]) static String valueOf(Object ob) static String valueOf(char chars[ ],int startIndex, int numChars) UNIT I 104
- 105. 105 UNIT-I For objects, valueOf() calls the toString( ) method on the object. Every class implements toString( ) because it is defined by Object. The default implementation of toString( ) is sufficient. We can override toString( ) and provide our own string representations for objects. The syntax is: String toString( ) String Conversion and toString( ): UNIT I 105
- 106. 106 UNIT-I Example: class Rect{ int length,breadth; Rect(intx,int y) { length=x; breadth=y; } } class Cube { int length,width,height; Cube(int x,int y,int z) { length=x; width=y; height=z; } public String toString( ) { return "Hai I am instance of Cube class"; } } class String1 { public static void main(String args[]) { Rect r1=new Rect(10,20); String s1=“Rect:”+r1; System.out.println(s1); Cube b1=new Cube(10,20,30); String s2=“Cube:”+b1; System.out.println(s2); } } O/P : Rect:Rect@82ba41 Cube:Hai I am instance of Cube class UNIT I 106
- 107. 107 UNIT-I Character Extraction: String objectcannot be indexed as if they were a character array. Many of the String methods employ an index into the string for their operation beginning at zero. char charAt(int where) void getChars(int sourceStart, int sourceEnd, char target[ ], int targetStart) byte[ ] getBytes( ) char[ ] toCharArray( ) UNIT I 107
- 108. 108 UNIT-I String Comparision: boolean equals(Stringstr) boolean equalsIgnoreCase(String str) boolean regionMatches(int startIndex,String str2, int str2StartIndex, int numChars) boolean regionMatches(boolean ignoreCase, int startIndex,String str2, int str2StartIndex, int numChars) boolean startsWith(String str) boolean endsWith(String str) int compareTo(String str) <0 if invoking string<str >0 if invoking string>str 0 if two strings are equal UNIT I 108
- 109. 109 UNIT-I Searching Strings: int indexOf(intch) for first occurrence int lastIndexOf(int ch) for last occurrence int indexOf(String str) int lastIndexOf(String str) int indexOf(int ch, int startIndex) int lastIndexOf(int ch, int startIndex) int indexOf(String str, int startIndex) int lastIndexOf(String str, int startIndex) startIndex specifies the index at which point the search begins. UNIT I 109
- 110. 110 UNIT-I Modifying a String: Stringsubstring(int startIndex) String substring(int startIndex, int endIndex) String concat(String str) String replace(char original, char replacement) String replace(CharSequence original, CharSequence replacement) Added in J2SE 5 String trim( ) UNIT I 110
- 111. 111 UNIT-I Changing the Caseof Characters within a String: String toLowerCase( ) String toUpperCase( ) UNIT I 111
- 112. 112 UNIT-I Some other StringMethods: String replaceAll(String regExp,String newStr) int codePointAt(int i) Added by J2SE 5 int codePointBefore(int i) “ int codePointCount(int start,int end) “ boolean contains(CharSequence str) “ boolean contentEquals(CharSequence str) “ boolean contentEquals(StringBuffer str) static String format(String fmtstr,Object … args) “ static String format(Locale loc, String fmtstr, Object … args) “ boolean matches(String regExp) int offsetByCodePoints(int start, int num) “ String replaceFirst(String regExp,String newStr) String[ ] split(String regExp) String[ ] split(String regExp, int max) CharSequence subSequence(int startIndex, int stopIndex) UNIT I 112
- 113.
- 114. 114 UNIT-I StringBuffer Constructors: StringBuffer( )16 characters StringBuffer(int size) StringBuffer(String str) str+16 characters StringBuffer(CharSequence chars) UNIT I 114
- 115. 115 UNIT-I Methods: int length( )string length int capacity( ) total allocated capacity void ensureCapacity(int capacity) preallocate void setLength(int len) char charAt(int where) void setCharAt(int where, char ch) void getChars(int sourceStart,int sourceEnd,char target[ ],int targetStart) Ensures that the capacity of the buffer is at least equal to the specified minimum. The new capacity is the larger of: a. The minimumCapacity argument. b. Twice the old capacity, plus 2. UNIT I 115
- 116. 116 UNIT-I StringBuffer append(String str) StringBufferappend(int num) StringBuffer append(Object obj) StringBuffer insert(int index, String str) StringBuffer insert(int index, char ch) StringBuffer insert(int index, Object obj) StringBuffer reverse( ) StringBuffer delete(int startIndex, int endIndex) StringBuffer deleteCharAt(int loc) StringBuffer replace(int startIndex,int endIndex,String str) String substring(int startIndex) String substring(int startIndex, int endIndex) Methods: UNIT I 116
- 117.
- 118. UNIT-I 118 ► Inheritanceis the process by which one object acquires the properties of another object. Definition: ► The class that is inherited is called a superclass or baseclass. ► The class that does the inheriting is called a subclass or derivedclass. ► Subclass is a specialized version of a superclass. UNIT I 118
- 119. UNIT-I 119 Types ofInheritance: UNIT I 119
- 120. UNIT-I 120 The generalform of a class definition that inherits a superclass uses the keyword extends and is shown as: class subclass-name extends superclass-name { //body of class } Syntax: UNIT I 120
- 121. UNIT-I 121 Sample program:Single Inheritance class A { int i,j; void show( ) { System.out.println(“i=”+i+” j=“+j); } } class B extends A { int p,q; void display( ) { System.out.println(“p=“+p+” q=“+q); } void all( ) { System.out.println(“i=”+i+” j=“+j+ “ p=“+p+” q=“+q); } } class InheritanceDemo1 { public static void main(String args[ ]) { A obj1=new A( ); B obj2=new B( ); obj1.i=10; obj1.j=20; obj2.i=30; obj2.j=40; obj2.p=50; obj2.q=60; obj1.show( ); obj2.display( ); obj2.all( ); obj2.show( ); } } O/P: i=10 j=20 p=50 q=60 i=30 j=40 p=50 q=60 i=30 j=40 UNIT I
- 122. UNIT-I 122 Java supportsthe following access specifiers(Modifiers) public private protected No modifier(default) Although a subclass includes all of the members of its superclass, it cannot access those members of the superclass that have been declared as private. Member Access: UNIT I 122
- 123. UNIT-I 123 Sample program:Use of private keyword class A { private int i,j; void show( ) { System.out.println(“i=”+i+” j=“+j); } } class B extends A { int p,q; void display( ) { System.out.println(“p=“+p+” q=“+q); } void all( ) { System.out.println(“i=”+i+” j=“+j+ “ p=“+p+” q=“+q); } } class InheritanceDemo2 { public static void main(String args[ ]) { A obj1=new A( ); B obj2=new B( ); obj1.i=10; obj1.j=20; obj2.i=30; obj2.j=40; obj2.p=50; obj2.q=60; obj1.show( ); obj2.display( ); obj2.all( ); obj2.show( ); } } Compile time ERROR UNIT I 123
- 124. UNIT-I 124 Superclass variablereferencing a subclass object: ► A reference variable of a superclass can be assigned a reference to any subclass derived from that superclass. UNIT I 124
- 125. UNIT-I 125 Sample program:Superclass variable referencing a subclass object class A { int i,j; void show( ) { System.out.println(“i=”+i+” j=“+j); } } class B extends A { int p,q; void display( ) { System.out.println(“p=“+p+” q=“+q); } void all( ) { System.out.println(“i=”+i+” j=“+j+ “ p=“+p+” q=“+q); } } class InheritanceDemo3 { public static void main(String args[ ]) { A obj1=new A( ); B obj2=new B( ); obj1.i=10; obj1.j=20; obj2.i=30; obj2.j=40; obj2.p=50; obj2.q=60; obj1.show( ); obj1=obj2; obj1.show( ); } } O/P: i=10 j=20 i=30 j=40 UNIT I
- 126. UNIT-I 126 super keyword: superhas two general forms: 1) To call the superclass constructor. 2) To access a member of the superclass. Whenever a subclass needs to refer to its immediate superclass, it can do so by use of the keyword super. UNIT I 126
- 127. UNIT-I 127 super tocall the superclass constructor: ► A subclass can call a constructor defined by its superclass by use of the following form of super: super(parameter-list) Note: super( ) must always be the first statement inside a subclass constructor. UNIT I 127
- 128. 128 class A{ int i,j; A( ){ System.out.println(“A default”); } A(int a, int b){ i=a; j=b; System.out.println(“A with 2 args”); } void show( ){ System.out.println(“i=”+i+” j=“+j); }} class B extends A{ int p,q; B( ){ System.out.println(“B default”); } B(int a, int b, int c, int d){ super(a,b); p=c; q=d; Sample program: super(parameter-list) System.out.println(“B with 4 args”); } void all( ){ System.out.println(“i=”+i+” j=“+j+“ p=“+p+” q=“+q); }} class SuperConstructor{ public static void main(String args[ ]){ A obj1=new A( ); B obj2=new B(30,40,50,60); obj1.show( ); obj2.all( ); obj2.show( ); }} O/P: A default A with 2 args B with 4 args i=0 j=0 i=30 j=40 p=50 q=60 i=30 j=40 UNIT I
- 129. UNIT-I 129 ► Thissecond form of super is most applicable to situations in which member names of a subclass hide members by the same name in the superclass. Second use of super keyword; The general form is: super.member ► The super always refers to the superclass of the subclass in which it is used. UNIT I 129
- 130. 130 class A{ int i,j; A( ){ System.out.println(“A default”); } A(int a, int b){ i=a; j=b; System.out.println(“A with 2 args”); } void show( ){ System.out.println(“i=”+i+” j=“+j); }} class B extends A{ int i, j, p, q; B( ){ System.out.println(“B default”); } B(int a, int b, int c, int d){ super(a,b); i=c; j=d; Sample program: super.member System.out.println(“B with 4 args”); } void all( ){ System.out.println(“Ai=”+super.i+”Aj=“+ super.j+“ i=“+i+” j=“+j); }} class SuperMember{ public static void main(String args[ ]){ A obj1=new A( ); B obj2=new B(30,40,50,60); obj1.show( ); obj2.all( ); obj2.show( ); }} O/P: A default A with 2 args B with 4 args i=0 j=0 Ai=30 Aj=40 i=50 j=60 i=30 j=40 130
- 131. UNIT-I 131 Multilevel Inheritance: subclassof A superclass of C superclass of B subclass of B UNIT I 131
- 132. UNIT-I 132 class A { inti,j; A( ) { System.out.println("A default"); } } class B extends A { int p,q; B( ) { System.out.println("B default"); } } Sample Program: Multilevel Inheritance O/P: ? class C extends B { int x,y; C( ) { System.out.println("C default"); } } class ConstructorOrder1 { public static void main(String args[ ]) { C c1=new C(); } } UNIT I 132
- 133. UNIT-I 133 ► Ifsuper( ) is not used, then the default or parameter less constructor of each superclass will be executed. In what order Constructors are called: ► In a class hierarchy, constructors are called in the order of derivation, from superclass to subclass. ► Since super( ) must be the first statement executed in a subclass constructor, this order is the same whether or not super( ) is used. UNIT I 133
- 134. UNIT-I 134 class Cextends B { int x,y; C( ) { System.out.println("C default"); } C(int a,int b,int c,int d,int e,int f) { super(a,b,c,d); x=e; y=f; System.out.println("C 6 args"); } void display( ) { System.out.println("i="+i+"j="+j+"p="+p+"q="+ q+"x="+x+"y="+y); }} class ConstructorOrder2 { public static void main(String args[]) { C c1=new C(10,20,30,40,50,60); c1.display(); }} class A{ int i,j; A( ) { System.out.println("A default"); } A(int a, int b) { i=a; j=b; System.out.println("A 2 args"); }} class B extends A { int p,q; B( ) { System.out.println("B default"); } B(int a,int b,int c,int d) { super(a,b); p=c; q=d; System.out.println("B 4 args"); }} Sample Program: Multilevel Inheritance UNIT I 134
- 135.
- 136. UNIT-I 136 Method Overriding: ►Whena method in a subclass has the same name and type signature as a method in its superclass, then the method in the subclass is said to override the method in the superclass. ► When an overriden method is called from within a subclass, it will always refer to the version of that method defined by the subclass. ► The version of the method defined by the superclass will be hidden. ► The superclass version of an overridden method can be accessed using super. UNIT I 136
- 137. UNIT-I 137 class A{ inti, j; void show( ){ System.out.println(“This is in A’s show “); }} class B extends A{ int p, q; void show( ){ super.show( ); System.out.println(“This is in B’s show “); }} class Override{ public static void main(String args[ ]){ A obj1=new A( ); B obj2=new B( ); obj1.show( ); obj2.show( ); }} Sample program: Method Overriding O/P: This is in A’s show This is in A’s show This is in B’s show UNIT I 137
- 138. UNIT-I 138 Dynamic MethodDispatch: Dynamic method dispatch is the mechanism by which a call to an overridden function is resolved at run time, rather than compile time. Java implements run-time polymorphism using dynamic method dispatch. UNIT I 138
- 139. UNIT-I 139 class A{ void callme( ) { System.out.println("A's method"); } } class B extends A { void callme( ) { System.out.println("B's method"); } } class C extends A { void callme( ) { System.out.println("C's method"); } } class DynamicMethodDispatch { public static void main(String args[]) { A a1=new A( ); B b1=new B( ); C c1=new C( ); A p1; p1=a1; p1.callme( ); p1=b1; p1.callme( ); p1=c1; p1.callme(); } } Sample program: Dynamic Method Dispatch O/P:- A’s method B’s method C’s method UNIT I 139
- 140. UNIT-I 140 Abstract classes: Anabstract method is a method without implementation. The general form is: abstract type name(parameter-list); Abstract methods must be overridden(implemented) in the subclasses. Any class that contains one or more abstract methods must be declared abstract. An abstract class cannot be directly instantiated with the new keyword. We cannot declare abstract constructors or abstract static methods. Any subclass of an abstract class must either implement all of the abstract methods in the superclass or be itself declared abstract. An abstract class reference can point to a subclass object. UNIT I 140
- 141. UNIT-I 141 abstract classA { void show( ) { System.out.println("A's show method"); } abstract void display(int x,int y); } class B extends A { void m1( ) { System.out.println("Method m1"); } void display(int x, int y) { System.out.println("Param1="+x+ " Param2="+y); } } Sample program1: Abstract classes O/P:- Param1=10 Param2=20 class AbstractClass { public static void main(String args[ ]) { B b1=new B(); b1.display(10,20); } } UNIT I 141
- 142. UNIT-I 142 Sample program2:Abstract classes class AbstractClass2 { public static void main(String args[ ]) { B b1=new B( ); b1.display(10,20); A a1; a1=b1; a1.display(30,40); } } O/P:- Param1=10 Param2=20 Param1=30 Param2=40 abstract class A { void show( ) { System.out.println("A's show method"); } abstract void display(int x,int y); } class B extends A { void m1( ) { System.out.println("Method m1"); } void display(int x, int y) { System.out.println("Param1="+x+ " Param2="+y); } } UNIT I 142
- 143. UNIT-I 143 final keyword: finalcan be applied for variables, methods and classes. A final variable is a constant. Methods declared as final cannot be overridden. Classes declared as final cannot be inherited. Declaring a class as final implicitly declares all of its methods as final. UNIT I 143
- 144. 144 Base class Object: Object class contains the following methods: Object clone( ) boolean equals(Object object) void finalize( ) Class getClass( ) int hashCode( ) void notify( ) void notifyAll( ) String toString( ) void wait( ) void wait(long milliseconds) void wait(long milliseconds, int nanoseconds) Object is superclass of all other classes. 144
- 145. UNIT-I 145 Subclass, Subtypeand Substitutability: When new classes are constructed using inheritance from existing classes, the argument used to justify the validity of substitutability is as follows: • Instances of the subclass must possess all data fields associated with the parent class • Instances of the subclass must implement, through inheritance atleast all functionality defined for the parent class. • An instance of a child class can mimic the behavior of the parent class and should be indistinguishable from an instance of the parent class if substituted in a similar situation. UNIT I 145
- 146. UNIT-I 146 Subclass, Subtypeand Substitutability: The term subtype is used to describe the relationship between types that explicitly recognizes the principle of substitution. Type B is considered to be a subtype of A if two conditions hold •An instance of B can legally be assigned to a variable declared as type A. •This value can then be used by the variable with no observable change in behavior. The term subclass refers to the mechanism of constructing a new class using inheritance. UNIT I 146
- 147. UNIT-I 147 Forms ofInheritance: Inheritance is employed in a variety of ways. The various forms of inheritance: Inheritance for Specialization Inheritance for Specification Inheritance for Construction Inheritance for Extension Inheritance for Limitation Inheritance for Combination UNIT I 147
- 148. UNIT-I 148 Benefits ofInheritance: Some of the important benefits of inheritance: Software Reusability Increased Reliability Code Sharing Consistency of Interface Software Components Rapid Prototyping Polymorphism and Frameworks Information Hiding UNIT I 148
- 149. UNIT-I 149 Costs ofInheritance: Although the benefits of inheritance are great, almost nothing is without cost of one sort or another. Some of the costs of inheritance are: Execution Speed Program Size Message-Passing Overhead Program Complexity UNIT I 149