JAVA Object Oriented Programming (OOP)
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JAVA Object Oriented Programming (OOP)

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JAVA Object Oriented Programming (OOP) JAVA Object Oriented Programming (OOP) Presentation Transcript

  • Lesson 1 Introduction to Object-Oriented Programming Prof. Erwin M. Globio, MSIT Java Training Specialist http://eglobiotraining.com
  • Object Oriented Programming  Model Real World Objects  Encapsulate Data and Function
  • Java is used for Networking  Has many classes to program Internet communications  Java-enabled devices  mobile phones  Web pages with additional animation and functionality  Java servlets
  • Java is Simple  Derived from C/C++  Simpler than C/C++.  No preprocessors  Pointers were eliminated  Common data structures that use pointers such as stacks, lists and trees are available
  • Java is Robust  Employs strong type checking  Every data structure is defined and its type is checked during compilation and runtime  Built-in exception handling  Garbage collection is done automatically
  • Java is Dynamic  There are many available Java resources in the Internet.  Using interfaces  Classes are dynamically loaded.
  • Java is Secure  System breakers can not gain access to system resources  the Java bytecode verifier  loaded classes can not access the file system  a public-key encryption system (in the future)
  • Java is Free  Java can be downloaded from the Internet for FREE  Just visit http://java.sun.com/
  • Java is Portable You can compile your Java code from the command line. SYNTAX: javac <filename>.java EXAMPLE: javac Welcome.java
  • Java is Portable Java program can then execute on any machine which has the Java Virtual Machine, thus, making it portable. SYNTAX: java <filename> EXAMPLE: java Welcome
  • Java is Portable Java code (*.java) Java Compiler bytecodes (*.class) Java Virtual Machine MAC PC UNIX
  • IDE: BlueJ Download the appropriate version Check the system requirements
  • IDEDownload BlueJ:http://www.bluej.org/download/download.html Install J2SE 1.4.2 (Java 2 SDK version 1.4.2) or newer first before installing BlueJ
  • IDE: BlueJ Minimum Requirements:  Pentium II processor or its equivalent  64Mb main memory Recommended:  400MHz Pentium III processor or above and a 128Mb main memory
  • Launch BlueJ Let‟s make your first Java project using BlueJ…
  • Sample codespackage Group.Student; public class Welcome{ public void printWelcome() { System.out.println("Welcome to Java!"); //prints_a_msg } }
  • Sample codes /* This class contains the main() method */ package Group.Student; public class Main { public static void main(String args[]) { Welcome Greet= new Welcome(); Greet.printWelcome(); } }
  • Common Programming Errors  compile-time errors  runtime errors
  • Compile Time Error
  • Compile Time Error
  • Compile Time Error
  • Run-Time Error
  • Run-Time Error
  • Word Bank  class  object  interface  message  method  inheritance  encapsulation  compile-time errors  runtime errors
  • End of Lesson 1 Summary…
  • End of Lesson 2 Laboratory Exercise
  • Self-checkCreate a class and describe it in terms of its attributes (data) and functions(methods). Then, instantiate at least 2 objects. Use the tables below. //write the class name here //write the object name here Class Human Man //write the data of the class here //write the data of the object Name here Age Name: Jonathan Birthday Age: 29 Birthday: March 4, 1975 //write the methods of the class here //write the methods of the object Grow here Give_Name Grow Get_Name Give_Name Get_Age Get_Name Get_Age [http://www.techfactors.ph] TechFactors Inc. ©2005
  • Self-checkCreate a class and describe it in terms of its attributes (data) and functions(methods). Then, instantiate at least 2 objects. Use the tables below. //write the class name here //write the object name here //write the data of the object //write the data of the class here here //write the methods of the object here //write the methods of the class here
  • Skills Workout Type the Java program given in this lesson in the specified package. Compile and run it. If errors are encountered, debug it.
  • Lesson 2 Your First Java Program
  • Welcome.javapublic class Welcome{ public void printWelcome() { System.out.println("Welcome to Java!"); //prints_a_msg }}
  • Explaining Welcome.javaLine 1A single line comment.A comment is read by he java compiler but, as a command, it is actually ignored.Any text followed two slash symbols(//) is considered a comment. Example: // Welcome to Java
  • Explaining Welcome.javaLine 2 defines the beginning of the Welcome class. When you declare a class as public, it can be accessed and used by the other class.Notice that there is also an open brace to indicate the start of the scope of the class.To declare a class here is the syntax<method>class<class_name>Example: public class Welcome{
  • Explaining Welcome.java Line 3 shows the start of the method printWelcome(). Syntax : <modifier> <return_type> <method_name> (<argument_list>) { <statements>) }Void is the return type for the printWelcome()Method. A method that returns void returns nothing. Return type are discussed further in lesson 8Example: public void printWelcome() {
  • Explaining Welcome.javaLine 4 shows how to print text in java. Theprintln() method displays the message inside theparentheses on the screen, and then the cursor isplaced on the next line. If you want cursor to go tothe next available space after printing, use print()method.Syntax:System.out.println(String); Example: System.out.println("Welcome to Java!");
  • Explaining Welcome.javaLine 5 and 6 }} Contains closing braces. The braces on line 5 closes the method printWelcome() and the braces on line 6 closes the class Welcome.Take note that the opening brace on line 3 is paired with the closing brace on line 5 and the brace on line 2 is paired with the closing brace on line 6
  • Explaining Main.java /* This class contains the main() method */ public class Main { public static void main(String args[]) { Welcome Greet= new Welcome(); Greet.printWelcome(); } }
  • Explaining Main.javaLine 1-3Contains a multi-line comment. Anyting in between /* and */ is considered a comment./*This class contains the main() method */
  • Explaining Main.javaLine 5Declares the Main class. the brace after the class indicates the start of the class.public class Main {
  • Explaining Main.javaLine 6Program execution starts from line 6. The Java interpreter should see this main method definition as is, except for args which is user defined.public class Main {
  • Explaining Main.javaLine 7 shows how an object is defined in Java. Here, the object Greet is created. The word “Greet” is user defined. (You can even have your name in its place!). The general syntax for defining an object in Java is: Syntax:  <class_name> <object_name> = new<class_name>(<arguments>);Example: Welcome Greet= new Welcome();
  • Explaining Main.javaLine 8Illustrates how a method of a class is called. If you look at the Welcome class, you’ll notice that we declared a mehod named printWelcome().By declaring an instance of the Welcome class (in tis case, the Greet variable is an instance of a Welcome class, courtesy of line 7), you can execute the method withi the specific class.Syntax: <class_name>.<method_name>(<arguments>); Example: Greet.printWelcome();
  • Explaining Main.javaLine 9-10 }}Contains wo closing braces. The brace on line 9 closes the main method and brace on line 10 indicates the end of the scoope of the class Main.
  • Word Banknew - used in telling the compiler to create an object from the specified class.public - modifier that indicates a class, method, or class variable can be accessed by any object or method directly.
  • End of Lesson 2 Summary…
  • Syntax Review SYNTAX EXAMPLE/Spackage package Group.Student;<top_package_name>[.<subpackage_name>]*;import import School.Section.Student;<top_package_name>[.<subpackage_name>]. import School.Section.*;<class_name>;<modifier> class <class_name> public class First<class_name> <object_name> = new <class_name> Welcome Greet= new Welcome();(<arguments>);< package_name>.<class_name> <object_name> = School.Section.Student Alma = newnew <package_name>.<class_name>(<arguments>); School.Section.Student ();<modifier> <return_type> <method_name> public static void main(String args[])(<argument_list>) { <statements>} {} public void printWelcome( ) { } [http://www.techfactors.ph] TechFactors Inc. ©2005
  • Syntax Review SYNTAX EXAMPLE/SSystem.out.println(String); System.out.println("Welcome to Java!");System.out.print (String); System.out.print("Hello");/* /*multi-line comment This class contains the main() method*/ *///single line comment // author@ //prints_a_msg/** /**Java doc multi-line comment This method will compute the sum of two*/ integers and return the result. */
  • Self-checkBelow is a simple Java program that will print your name and age on thescreen. Fill the missing portions with the correct code. Type the program,compile and run it. First.java //filename 1 /* 2 This class contains the main() method 3 */ 4 package Group.Student; 5 6 public class First { 7 public static void main(String args[]) { 8 Name ____________= new Name(); 9 myName.________________(); 10 } 11 }
  • Self-checkBelow is a simple Java program that will print your name and age on thescreen. Fill the missing portions with the correct code. Type the program,compile and run it. Name.java //filename1 package Group.Student;2 // author@3 public class __________{4 public void printName() {5 System.out.print("____________");// prints your name6 System.out.println("____________");//prints your age7 }8 }
  • End of Lesson 2 Laboratory Exercise
  • Lesson 3 Data Types, Literals, Keywords and Identifiers
  • Magic wordsCasting – process of converting a value to the type of variable.Constant – identifier whose value can never be changed once initialized.Identifier – user-defined name for methods, classes, objects, variables and labels.
  • Literals – values assigned to variables or constantUnicode – universal code that has a unique number to represent each character.Variable – identifier whose value can be changed. Java keyword – word used by the Java compiler for a specific purpose
  • Java Keywords [http://www.techfactors.ph] TechFactors Inc. ©2005
  • Java Keywords Some key points about Java keywords: • const and goto are keywords but are not used in Java. • true and false are boolean literals that should not be used as identifiers. • null is also considered a literal but is not allowed as an identifier.
  • IdentifiersRules for Identifiers: • The first character of your identifier can start with a Unicode letter. • It can be composed of alphanumeric characters and underscores. • there is no maximum length • create identifiers that are descriptive of their purpose. • Your identifier must have no embedded spaces. • Special characters such as ? and like are not accepted.
  • Data Types Java has two sets of data types: • primitive • reference (or non-primitive).
  • Data Types Data Type Default boolean false char „u0000‟ byte 0 short 0 int 0 long 0 float 0L double 0.0D
  • Data Types Data Type Examples boolean true char „A‟,‟z‟,‟n‟,‟6‟ byte 1 short 11 int 167 long 11167 float 63.5F double 63.5
  • Variables  Variable Declaration Syntax: <data_type> <identifier>; Examples: boolean Passed; char EquivalentGrade’; byte YearLevel; short Classes; int Faculty_No; long Student_No; float Average;
  • Variables and Literals Variable and Literal Declaration Syntax: <data_type> <identifier>=<literal>; Examples: boolean Passed=true; char EquivalentGrade=’F’; byte YearLevel=2; short Classes=19; int Faculty_No=6781; long Student_No=76667; float Average=76.87F;
  • Variables and Literals  You can also declare several variables for a specific data type in one statement by separating each identifier with a comma(,)Examples: boolean Passed =true, Switch; char EquivalentGrade=’F’,ch1, ch2; byte Bytes, YearLevel =2; short SH, Classes =19; int Faculty_No =6781, Num1; long Student_No =76667, Employee_No, Long1; float Average=96.89F, Salary; double Logarithm=0.8795564564, Tax, SSS; String LastName=”Your LastName”,FirstName=”Your FirstName”, MiddleName;
  • ConstantsExample: static final String Student_ID=”098774656”;Syntax for declaring constants: static final <type> <identifier> = <literal>; final <type> <identifier> = <literal>;
  • Type Conversion/ CastingCasting • the process of assigning a value of a specific type to a variable of another type.• The general rule in type conversion is: • upward casts are automatically done. • downward casts should be expressed explicitly.
  • Sample Codepackage Group.Lesson3;public class Core{ public Core(){ } /** * The main method illustrates implicit casting from char to int * and explicit casting. */ public static void main(String[] args) { int x=10,Average=0; byte Quiz_1=10,Quiz_2=9; char c=a; Average=(int) (Quiz_1+Quiz_2)/2; //explicit casting x=c; //implicit casting from char to int System.out.println("The Unicode equivalent of the character a is : "+x); System.out.println("This is the average of two quizzes : "+Average); }}
  • End of Lesson 3 Summary…
  • Self-checkI. Write I if the given is not an acceptable Java identifier on the space provided before each number. Otherwise, write V.________________ 1.) Salary________________ 2.) $dollar________________ 3.) _main________________ 4.) const________________ 5.) previous year________________ 6.) yahoo!________________ 7.) else________________ 8.) Float________________ 9.) <date>________________10.) 2_VersionII. Write C if the given statement is correct on the space provided before each number. Otherwise, write I. Correct statements do not contain bugs.________________1.) System.out.print(“Ingat ka!”, V);________________2.) boolean B=1;________________3.) double=5.67F;________________4.) char c=(char) 56;________________5.) System.out.print(„ I love you! „);
  • Self-checkIII.Below is a simple Java program that will print your name and age on the screen. Fill the missing portions with the correct code. Type the program, compile and run it.public class First{ public ________________(){ }//Constructor for objects of class Core public static void main(String[] args) { int I=90; short S=4; ________________;//statement to cast I to S System.out.println(“I=___________________ );//print I System.out.println(“S=___________________ );//print S }}
  • End of Lesson 10 LABORATORY EXERCISE
  • Lesson 4 Java Operators
  • Operators • Unary • Binary • Ternary • Shorthand
  • Arithmetic Operator Operators + Addition - Subtraction * Multiplication / Division % Modulo ++ Increment -- Decrement
  • The Arithmetic_operators programpackage Group.Lesson4.Arithmetic;public class Arithmetic_operators{ public Arithmetic_operators() { } // Constructor public static void main(String[] args) { int x=30, y= 2; int Add=0,Subtract=0,Multiply=0,Divide=0; int Modulo=0,Inc1=0,Inc2=0,Dec1=0,Dec2=0; Add=x+y; Subtract=x-y; Multiply=x*y; Divide=(int)x/y; Modulo=x%y;
  • The Arithmetic_operators program (Continued) System.out.println("30+2="+Add+"n30-2="+Subtract);System.out.println("30*2="+Multiply+"n30/2="+Divide+"n30%2="+Modulo); System.out.println("x="+x+"ny="+y); x++; ++y; System.out.println("x="+x+"ny="+y); --x; y--; System.out.println("x="+x+"ny="+y); Inc1=x++; Inc2=++y; System.out.println("Inc1="+Inc1+"nInc2="+Inc2); System.out.println("x="+x+"ny="+y); Dec1=--x; Dec2=y--; System.out.println("Inc1="+Inc1+"nInc2="+Inc2); System.out.println("x="+x+"ny="+y); }}
  • The Arithmetic_operators program output [http://www.techfactors.ph] TechFactors Inc. ©2005
  • Relational Operator > Greater than >= Greater than or equal to < Less than <= Less than or equal to == Equal to != Not Equal to
  • The Relational_operators programpackage Group.Lesson4.Relational;public class Relational_operators{ public Relational_operators() { }// Constructor for objects of classRelational_operators public static void main(String[] args)//execution begins here { //local variables int x = 5, y = 7; boolean Relational_Equal=false, Relational_NotEqual=false; boolean Relational_LessThan=false, Relational_LessThanOrEqualTo=false; boolean Relational_GreaterThan=false; boolean Relational_GreaterThanOrEqualTo=false;
  • The Relational_operators program (Continued) //evaluate expressions Relational_Equal= x==y; Relational_NotEqual= x!=y; Relational_LessThan= x<y; Relational_LessThanOrEqualTo= x<=y; Relational_GreaterThan= x>y; Relational_GreaterThanOrEqualTo= x>=y; //print results System.out.println("x=5 y=7"); System.out.println("x==y "+Relational_Equal); System.out.println("x!=y "+Relational_NotEqual); System.out.println("x<y "+Relational_LessThan); System.out.println("x<=y"+Relational_LessThanOrEqualTo); System.out.println("x>y "+Relational_GreaterThan); System.out.println("x>=y"+Relational_GreaterThanOrEqualTo); }}
  • The Relational_operators program output [http://www.techfactors.ph] TechFactors Inc. ©2005
  • Logical Operator Operators Description ! NOT || OR && AND | short-circuit OR & short-circuit AND
  • Logical Operator- Truth Tables The NOT (!) operator Operand1 RESULT ! true false ! false true
  • Logical Operator- Truth Tables The OR (|) operator Operand1 Operand2 RESULT true | true true true | false true false | true true false | false false
  • Logical Operator- Truth Tables The XOR (^) operator Operand1 Operand2 RESULT true ^ true false true ^ false true false ^ true true false ^ false false
  • Logical Operator- Truth Tables The AND (&) operator Operand1 Operand2 RESULT true & true true true & false false false & true false false & false false
  • The Logical_operators programpackage Group.Lesson4.Logical;public class Logical_operators{ // Constructor for objects of class Logical_operators public Logical_operators(){} public static void main(String[] args)//execution begins here { //local variables int x = 6 , y = 7; boolean Logical_OR=false, Logical_OR_ShortCircuit=false; boolean Logical_AND=false, Logical_AND_ShortCircuit=false; boolean Logical_NOT=false, Logical_XOR=false; System.out.println("x=6 y=7"); Logical_OR_ShortCircuit= (x<y)| (x++==y); System.out.println("(x<y)| (x++==y) "+Logical_OR_ShortCircuit); Logical_OR= (x<y)||(x++==y); System.out.println("(x<y)| (x++==y) "+Logical_OR);
  • The Logical_operators program (Continued)Logical_AND_ShortCircuit=(x<y)& (x==y++);System.out.println("(x>y)& (x++==y) “ +Logical_AND_ShortCircuit);Logical_AND= (x<y)&&(x++==y);System.out.println("(x>y)&&(x++==y) "+Logical_AND);Logical_NOT= !(x>y)||(x++==y);System.out.println("!(x>y)||(x++==y) "+Logical_NOT);Logical_XOR= (x>y)^ (x++==y);System.out.println("(x>y)^ (x++==y) "+Logical_XOR);System.out.println("!((x>y)^ (x++==y)) "+!Logical_XOR);//NEGATE }
  • The Logical_operators program output [http://www.techfactors.ph] TechFactors Inc. ©2005
  • REVIEW RECALL: How do you get the equivalent of a certain number in bits?ANSWER: You divide the number by 2 until you reach 0. Jot down the remainder for each division operation and that‟s the equivalent. RECALL: How do you convert a bit sequence to integer? ANSWER: You multiply each bit by powers of 2. Then, add all the products to get the equivalent. RECALL: How many bits does an integer have? ANSWER: 16 bits Try converting 16 and 27 to bits. Hope you got these answers: 16=0000000000010000 27=0000000000011011
  • REVIEW If you have a negative number, you stillhave to convert the same way you would if itwere a positive number. Then, get thecomplement and add 1. That‟s it! Example: 4=0000000000000100 -4=1111111111111100
  • Bitwise Operator Operators Description ~ Complement & AND | OR ^ XOR (Exclusive OR) << Left Shift >> Right Shift >>> Unsigned Right Shift
  • Bitwise Operator - Truth Tables The BITWISE COMPLEMENT Operand1 RESULT~ 1 0~ 0 1
  • Bitwise Operator - Truth Tables The BITWISE OR (|)Operand1 Operand2 RESULT 1 | 1 1 1 | 0 1 0 | 1 1 0 | 0 0
  • Bitwise Operator - Truth Tables The BITWISE XOR (^) Operand1 Operand2 RESULT 1 ^ 1 0 1 ^ 0 1 0 ^ 1 1 0 ^ 0 0
  • Bitwise Operator - Truth Tables The BITWISE AND (&) Operand1 Operand2 RESULT 1 & 1 1 1 & 0 0 0 & 1 0 0 & 0 0
  • Bitwise Operator – Examplesx= 0000000000010000~x= 1111111111101111 x= 0000000000010000Therefore, ~x=-17. Left_shift= 0000000010000000x= 0000000000010000 Left_shift = 128y= 0000000000011011Or= 0000000000011011 z= 1111111111111100 Right_shift= 1111111111111111x= 0000000000010000 Right_shift= -1y= 0000000000011011And= 0000000000010000 Negative=1111111111111100 Negative=0011111111111111x= 0000000000010000 Negative= 1073741823y= 0000000000011011Xor= 0000000000001011
  • The Bitwise_operators programpackage Group.Lesson4.Bitwise;public class Bitwise_operators{ //Constructor for objects of class Bitwise_operators public Bitwise_operators() { } public static void main(String[] args)//execution begins here { //local variables int x = 16 , y = 27, z=-4, Negative=-4; int Complement=0,Or=0,And=0,Xor=0,Left_shift=0; int Right_shift=0, Unsigned_Right_shift=0; //operations Complement = ~x; Or = x|y; And = x&y; Xor = x^y; Left_shift = x<<3; Right_shift = z>>2; Unsigned_Right_shift= Negative>>>2;
  • The Bitwise_operators program (continued)//print results System.out.println("x=16 y=7 z=-4"); System.out.println("~x = "+Complement); System.out.println("x|y = "+Or); System.out.println("x&y = "+And); System.out.println("x^y = "+Xor); System.out.println("x<<3 = "+Left_shift); System.out.println("z>>2 = "+Right_shift); System.out.println("Negative>>>2 = "+Unsigned_Right_shift); }}
  • The Bitwise_operators program output
  • Shorthand Operator with Assignment Operators Description += Assignment With Addition -= Assignment With Subtraction *= Assignment With Multiplication /= Assignment With Division %= Assignment With Modulo &= Assignment With Bitwise And |= Assignment With Bitwise Or ^= Assignment With Bitwise XOR <<= Assignment With Left Shift >>= Assignment With Right Shift >>>= Assignment With Unsigned Right Shift
  • The Shorthand_operators programpackage Group.Lesson4.Shorthand;public class Shorthand_operators{ //Constructor for objects of class Shorthand_operators public Shorthand_operators(){ } public static void main(String[] args)//execution begins here { //local variables int Assign_With_Addition=4, Assign_With_Subtraction=4, Assign_With_Multiplication=4; double Assign_With_Division=7; int Assign_With_Modulo=7, Assign_With_Bitwise_And=7; int Assign_With_Bitwise_Or=23, Assign_With_Bitwise_XOR=23, Assign_With_LeftShift=23; int Assign_With_RightShift=10, Assign_With_UnsignedRightShift=10; Assign_With_Addition +=2; Assign_With_Subtraction -=2; Assign_With_Multiplication *=2; Assign_With_Division /=2; Assign_With_Modulo %=2; Assign_With_Bitwise_And &=2; Assign_With_Bitwise_Or |=2; Assign_With_Bitwise_XOR ^=2; Assign_With_LeftShift <<=2; Assign_With_RightShift >>=2; Assign_With_UnsignedRightShift >>>=2; System.out.println(" Results");
  • The Shorthand_operators program (continued) System.out.println("Assign_With_Addition+=2 "+Assign_With_Addition); System.out.println("Assign_With_Subtraction-=2 "+Assign_With_Subtraction); System.out.println("Assign_With_Multiplication*=2 "+Assign_With_Multiplication); System.out.println("Assign_With_Division/=2 "+Assign_With_Division); System.out.println("Assign_With_Modulo%=2 "+Assign_With_Modulo ); System.out.println("Assign_With_Bitwise_And&=2 "+Assign_With_Bitwise_And); System.out.println("Assign_With_Bitwise_Or|=2 "+Assign_With_Bitwise_Or ); System.out.println("Assign_With_Bitwise_XOR^=2 "+Assign_With_Bitwise_XOR); System.out.println("Assign_With_LeftShift<<=2 "+Assign_With_LeftShift); System.out.println("Assign_With_RightShift>>=2 "+Assign_With_RightShift); System.out.println("Assign_With_UnsignedRightShift>>>=2 "+Assign_With_UnsignedRightShift); }}
  • The Shorthand_operators program output
  • Operator Precedence
  • Word Bank  expression  boolean expressions  truth value  truth table  shorthand operators  bit  sign bit
  • End of Lesson 4 Summary…
  • Self-checkEvaluate the given expressions/statements. Writethe result on the blanks provided before eachnumber. Given that a=3, b=4,c=6. 1.x=a++; 2.y=--b; 3.!((++a)!=4)&&(--b==4)) 4.(c++!=b)|(a++==b) 5.t=a+b*c/3-2;
  • Lesson 5 Decisions
  • Decision makingIn life we make decisions. Many times our decision are based on how we evaluate the situation. Certain situation need to be evaluated carefully in order to make the correct results or decision.
  • In Java , decisions are made using statements like if, if else, nested-if and switch.In this lesson , we will examine hot these conditional statements are applied to simple programming problems.
  • Decision Statements If Statement: public class If_Statement { public static void main (String [] args) { int x = 0; System.out.println ("Value is:" + x); if(x%2==0) { System.out.println ("VAlue is an even number."); } if (x%2 ==1) { System.out.println ("Value is an odd number."); } } • }
  • Wrapper Class Primitive Data Wrapper Class Type boolean Boolean char Character byte Byte short Short int Integer long Long float Float double Double
  • if Statement Syntax: if (<boolean condition is true>) { <statement/s> } Example: if(x!=0){ x=(int)x/2; }
  • The If_Statement programpackage Lesson5.If;import java.io.*;public class If_Statement{ //Constructor for objects of class If_Statement public If_Statement(){ } public static void main(String[] args) throws IOException { BufferedReader dataIn=new BufferedReader(new InputStreamReader(System.in)); int x=0; String Str_1; System.out.print("Enter an integer value: "); Str_1=dataIn.readLine(); x=Integer.parseInt(Str_1); if(x!=0){ x=(int)x/2; } System.out.println("x= "+x); }}
  • if-else Statement Example: if (A%2==0) { System.out.println (A+" is an EVEN number"); } else { System.out.println (A+" is an ODD number"); } Syntax: if (<boolean condition is true>){ <statement/s> } else { <statement/s> }
  • The IfElse programpackage Lesson5.If_Else;import java.io.*;public class IfElse { public IfElse() { } public static void main(String[] args)throws IOException { BufferedReader dataIn=new BufferedReader(new InputStreamReader(System.in)); //declare local variables int A=0; String Str_A; //input System.out.print("Enter an integer value for A: "); Str_A=dataIn.readLine(); A=Integer.parseInt(Str_A); //determine if input is odd or even and print if (A%2==0) { System.out.println (A+" is an EVEN number"); } else { System.out.println (A+" is an ODD number"); } }}
  • nested-if Statement Syntax: if (<boolean condition is true>){ <statement/s> } else if (<boolean condition is true>) { <statement/s> } else { <statement/s> }
  • nested-if StatementExample:if (number1>number2) { System.out.println (number1+" is greater than "+number2);} else if (number1<number2){ System.out.println (number1+" is less than "+number2);} else {//number1==number2 System.out.println (number1+" is equal to "+number2);}
  • The NestedIf program and outputpublic class NestedIf { public NestedIf() { } public static void main(String[] args)throws IOException { BufferedReader dataIn=new BufferedReader(new InputStreamReader(System.in)); //declare local variables double number1=0.0,number2=0.0; String Str_number1,Str_number2; //input Str_number1 and convert it to an integer (number1) System.out.print("Enter a number: "); Str_number1=dataIn.readLine(); number1=Double.parseDouble(Str_number1); //input Str_number2 and convert it to an integer (number2) System.out.print("Enter another number: "); Str_number2=dataIn.readLine(); number2=Double.parseDouble(Str_number2); //determine if number1 is greater than, less than or equal to number2 if (number1>number2) { System.out.println (number1+" is greater than "+number2); } else if (number1<number2){ System.out.println (number1+" is less than "+number2); } else {//number1==number2 System.out.println (number1+" is equal to "+number2); } }}
  • switch Statement Syntax: switch(<expression>) { case <constant1>: <statements> break; case <constant2>: <statements> break; : : default: <statements> break; }
  • switch StatementExample:switch(month){ case 1:System.out.println("January has 31 days"); break; case 2:System.out.println("February has 28 or 29 days"); break; case 3:System.out.println("March has 31 days"); . . . default:System.out.println("Sorry that is not a valid month!"); break; }
  • The Switch_case programpublic Switch_case(){ }//Constructor for objects of class Switch_case public static void main(String[] args) throws IOException{ BufferedReader dataIn=new BufferedReader(newInputStreamReader(System.in)); int month=0; String Str_month; System.out.print("Enter month [1-12]: "); Str_month=dataIn.readLine(); month=Integer.parseInt(Str_month); switch(month){ case 1:System.out.println("January has 31 days"); break; case 2:System.out.println("February has 28 or 29 days"); break; case 3:System.out.println("March has 31 days"); break; case 4:System.out.println("April has 30 days"); break; case 5:System.out.println("May has 31 days"); break;
  • The Switch_case program (continued) and outputcase 6:System.out.println("June has 30 days"); break;case 7:System.out.println("July has 31 days"); break;case 8:System.out.println("August has 31 days"); break;case 9:System.out.println("September has 30 days"); break;case 10:System.out.println("October has 31 days"); break;case 11:System.out.println("November has 30 days"); break;case 12:System.out.println("December has 31 days"); break;default:System.out.println("Sorry that is not a valid month!"); break; }}}
  • Word Bank  Wrapper class
  • End of Lesson 5 Summary…
  • End of Lesson 10 LABORATORY EXERCISE
  • Syntax Review SYNTAX EXAMPLE/Sif (<boolean condition is if(x!=0){true>) { x=(int)x/2;<statement/s> }}if (<boolean condition is if (A%2==0) {true>){ System.out.println (A+" is EVEN");<statement/s> }} elseelse { { System.out.println (A+" is ODD ");<statement/s> }}
  • SYNTAX EXAMPLE/SSyntax Reviewif (<boolean condition is true>){ if (number1>number2) {<statement/s> System.out.println (number1+" is greater than "+number2);} } else if (number1<number2){else if (<boolean condition is true>) { System.out.println (number1+" is less than "+number2);<statement/s> } else {//number1==number2} System.out.println (number1+" is equal to "+number2);else{ }<statement/s>}switch(<expression>) { switch(Number){ case case 1:System.out.println("One ");<constant1>:<statements> break; break; case 2:System.out.println("Two"); case break;<constant2>:<statements> case 3:System.out.println("Three"); break; break; : default:System.out.println("Sorry!"); : break; default: } <statements> break;}
  • Self-check In the next slide is a simple Java programthat will determine if a number is zero, positive ornegative then print the appropriate message onthe screen. Fill the missing portions with thecorrect code. Type the program, then compile andrun it.
  • Self-check public class NestedIf { public NestedIf() { }//constructor public static void main(String[] args) { int number=3; if (__________) // FILL-IN THE BLANK { System.out.println (number+” is ZERO!”); } else if (___________) //FILL-IN THE BLANK { System.out.println (number+" is a POSITIVE number!”); } else { System.out.println (number+" is a NEGATIVE number!”); } } }
  • Lesson 6 Loops
  • General Topics • for structure • while structure • do-while structure
  • loop A loop is a structure in Java that permits a set of instructions to be repeated
  •  The for loop is usually used when the number of iterations that needs to be done is already known. The while loop checks whether the prerequisite condition to execute the code within the loop is true or not. If it is true, then the code loop is executed. The do-while loop executes the code within it first regardless of whether the condition is true or not before testing the given condition.
  • 3 Main Parts of for loopInitialization - initial values of variables that will be used in the loop.Test condition - a boolean expression that should be satisfied for the loop to continue executing the statements within the loop’s scope; as long as the condition is true.Increment/Operations- dictates the change in value of the loop control variable everytime the loop is repeated.
  • for loop Example: for(int Ctr=1;Ctr<=5;Ctr++){ System.out.println(Ctr); } Syntax: for (<initialization>;<condition>;<increment>) { <statement/s> }
  • The For_loop program and outputpackage Lesson6.For;public class For_loop{ public For_loop() { } public static void main(String[] args) { for(int Ctr=1;Ctr<=5;Ctr++){ System.out.println(Ctr); } }}
  • while loop Example: int Ctr=1; while(Ctr<=5){ System.out.println(Ctr); Ctr++; } Syntax: while (boolean condition is true) { <statement/s> }
  • Sample Code and outputpublic class While_Loop{ //Constructor for objects of class While_loop public While_Loop() { } public static void main(String[] args) { int Ctr=1; while(Ctr<=5){ System.out.println(Ctr); Ctr++; } }}
  • do-while loop Example: int Ctr=1; do{ System.out.println(Ctr); Ctr++; }while(Ctr<=5); Syntax: do { <statement/s> } while (<boolean condition is true>);
  • Sample Codepublic class DoWhile{ public DoWhile() { } public static void main(String[] args) { int Ctr=1; do{ System.out.println(Ctr); Ctr++; }while(Ctr<=5); }}
  • End of Lesson 6 Summary…
  • Self-check In the next slides are three simple Java programs. Fill the missing portions with the correct code. Type the programs, compile and run them.
  • Self-check (For_loop2) public class For_loop2 { //Constructor for objects of class For_loop2 public For_loop2() { } /** * main()-prints all even numbers from 1-10 automatically using a for loop * * @param String[] args * @return nothing */ public static void main(String[] args) { for(int Ctr=____;Ctr<=_____;Ctr____){ System.out.println(Ctr); } } }
  • Self-check (DoWhile2) public class DoWhile2 { //Constructor for objects of class DoWhile2 public DoWhile2() { } /** * main()-prints the numbers 1-10 automatically using a do_while loop * * @param String[] args * @return nothing */ public static void main(String[] args) { int Ctr=________; do{ System.out.println(Ctr); Ctr______; }while(Ctr<=_________); } }
  • Self-check (While_Loop2) public class While_Loop2 { //Constructor for objects of class While_loop2 public While_Loop2() { } /** * main()-prints odd numbers from 2 to 20 automatically using a while loop * * @param String[] args * @return nothing */ public static void main(String[] args) { int Ctr=____________; while(Ctr<=__________){ System.out.println(Ctr); Ctr_______________; } } }
  • End of Lesson LABORATORY EXERCISE
  • More Loops
  • General Topics • Nested loops • continue • break
  • Nested_For loops The Nested_For program prints the multiplication table. To do this, it has two loops. One loop is inside the other. This is why it is called a nested loop.
  • Nested_For loops public class Nested_For { // Constructor for objects of class Nested_For public Nested_For(){ } public static void main(String [] args) { for(int Row=1;Row<=10;Row++){ for(int Column=1;Column<=10;Column++){ System.out.print(Row*Column+"t"); } System.out.println(); } } }
  • Nested_For loops – how it behaves To see how this program behaves at any given time, we need to set breakpoints. To do that, just click on line number. Click on line 15.
  • Nested_For loops – how it behaves Run the program by right-clicking on the Nested_For icon, click on void main(String [] args). Then, click on the Ok button.
  • Nested_For loops – how it behaves – how it behaves
  • Nested_For loops – how it behaves
  • Nested_For loops – Output
  • Continue_Loop The difference is the inclusion of the if statement on line 17 and the continue statement on line 18.
  • Continue_Loop public class Continue_Loop { // Constructor for objects of class Continue_Loop public Continue_Loop(){ } public static void main(String [] args) { for(int Row=1;Row<=10;Row++){ for(int Column=1;Column<=10;Column++){ if(Column==4){ continue; } System.out.print(Row*Column+"t"); } System.out.println(); } } }
  • Continue_Loop - Output The column containing the multiples of 4 is not included.
  • Loop_BreakThis program is againsimilar to the previousprograms in this lesson,except for the inclusionof the if and breakstatements. The outputshows 3 columns only.
  • Loop_Break public class Loop_Break { //Constructor for objects of class Loop_Break public Loop_Break(){ } public static void main(String [] args) { for(int Row=1;Row<=10;Row++){ for(int Column=1;Column<=10;Column++){ if(Column==4){ break; } System.out.print(Row*Column+"t"); } System.out.println(); } } }
  • Labels public class Labels { //Constructor for objects of class Labels public Labels() { } public static void main(String [] args) { here: for(int Row=1;Row<=10;Row++){ for(int Column=1;Column<=10;Column++){ System.out.print(Row*Column+"t"); if(Column==4){ break here; } } System.out.println(); } } }
  • Word Bank Nested loops
  • Self-checkI. A Java program that prints the multiplication table is given using nestedwhile loops. Fill-in the missing portions. public class Multiplication_Table { // Constructor for objects of class Multiplication_Table public Multiplication_Table (){ } public static void main(String [] args) { int Row=_______; //indicate the initial value while(Row<____){ Row++; int Column=_____; //indicate the initial value while(Column<_____){ Column++; System.out.print(Row*Column+"t"); } System.out.println(); } } }
  • Self-check II. A Java program that prints the given output using nested do-while loops. Fill-in the missing portions.
  • Self-check public class Table{ // Constructor for objects of class Table public Table(){ } public static void main(String [] args) { int Row=_______; //indicate the initial value do{ Row++; int Column=_____; //indicate the initial value do{ Column++; if(_______){ continue; } System.out.print(Row*Column+"t"); } while(Column<_____); System.out.println(); } while(Row<____); } }
  • LESSON 7 Exceptions
  • Exceptions Unexpected errors or events within our program
  • import java.io.*;public class Exception1{public static void main(String[] args){BufferedReader dataIn = new BufferedReader(new InputStreamReader(System.in)); int x=0; String Str_1; System.out.print(“Enter an integer value:”); try{ Str_1 = dataIn.readLine(); x = Integer.parseInt(Str_1); } catch(Exception e){ System.out.println(“Error reported”); } x = (int)x/2; System.out.println(“x= ”+x);}}
  • import java.io.*;public class Exception2{public static void main(String[] args){BufferedReader dataIn = new BufferedReader(new InputStreamReader(System.in));int x=0, y=0;String Str_1, Str_2;System.out.print(“Enter an integer value: ”);try{ Str_1 = dataIn.readLine(); System.out.print(“Enter another value: ”); Str_2 = dataIn.readLine(); x = Integer.parseInt(Str_1); y = Integer.parseInt(Str_2); x = x/y;}
  • catch(ArithmeticException e){ System.out.println(“Divide by zero error.”);}catch(NumberFormatException e){ System.out.println(“Invalid number entered.”);}catch(Exception e){ System.out.println(“Invalid number entered.”);}finally{ System.out.println(“x= ”+x);}}}
  • Exceptions Exception classes try catch finally
  • Exception classes Help handle errors Included within Java installation package
  • try-catch At least one catch for every try catch statements should catch different exceptions try-catch order catch immediately after a try
  • End of Lesson LABORATORY EXERCISE
  • Lesson 8 Classes
  • General Topics • Classes • Inheritance • Interface • Objects • Constructors • Overloading Methods • Overriding Methods
  • Classes
  • Accessibility
  • Syntax<modifier> class <class_name>[extends <superclass>] { <declaration/s>} Example: public class Student extends Person
  • Syntax <modifier> class <name> [extends <superclass>] [implements <interfaces>] { <declaration/s> } Example: public class Teacher extends Person implements Employee
  • Syntax <modifiers> class <class_name>{ [<attribute_declarations>] [<constructor_declarations>] [<method_declarations>] }
  • The Person program package Lesson8; public class Person extends Object { private String name; private int age; private Date birthday; // class constructor public Person() { name = "secret"; age = 0; birthday = new Date(7,7); } //overloaded constructor public Person(String name, int age, Date birthday){ this.name = name; this.age = age; this.birthday = birthday; }
  • The Person program (continued)//accessor methods - setters public void setName(String X){ name= X; } public void setAge(int X) { age=X; } public void setBirthday(Date X){ birthday=X; } public void setDetails(String X, int Y, Date Z){ name= X; age=Y; birthday = Z; } //accessor methods - getters public String getName(){ return name; }
  • The Person program (continued)public int getAge(){ return age; } //this method greets you on your bday and increments age public void happyBirthday(Date date){ System.out.println("Today is"+date.month+"/"+date.month+"/2005."); if (birthday.day == date.day && birthday.month == date.month){ System.out.println("Happy birthday, "+ this.name + "."); age++; System.out.println("You are now "+age+" years old."); } else { System.out.println( "Its not " + this.name + "s birthday today."); } }}
  • The Someone programpackage Lesson8;public class Someone{ public static void main (String args[]){ Date dateToday = new Date(3,7); Date bdayLesley= new Date(23,10); Person Angelina=new Person(); Student Stevenson = new Student("Stevenson",20,new Date(22,10),4); Student Allan =new Student(3); Teacher Lesley= new Teacher("Lesley",28,bdayLesley,14000.25); Angelina.setName("Angel"); Angelina.setAge(69); Angelina.setBirthday(dateToday); System.out.println("Greetings, "+Angelina.getName()); Angelina.happyBirthday(dateToday); System.out.println(); Allan.setDetails("Allan",20,new Date(3,5)); }
  • The Date programpackage Lesson8;public class Date{ // instance variables - replace the example below with your own int day, month, year; //Constructor for objects of class Date with no parameters public Date() { // initialize instance variables day = 1; month=1; year=2005; }
  • The Date program (continued)//Constructor for objects of class Date with day & month as parameters public Date(int this_Day,int this_Month) { // initialise instance variables if((this_Month>=1)&&(this_Month<=12)){ month=this_Month; switch(month){ case 1: case 3: case 5: case 7: case 8: case 10: case 12:if((this_Day>=1)&&(this_Day<=31)){day = this_Day;} else {day=1;} break; case 4: case 6: case 9: case 11:if((this_Day>=1)&&(this_Day<=30)){ day = this_Day;} else {day=1;} break; case 2:if((this_Day>=1)&&(this_Day<=28)){day = this_Day;} else {day=1;} break; } } else { month=1; } year=2005; }
  • The Date program (continued)public void print_Date(){//prints the date mm/dd/yyyy System.out.println(month+"/"+day+"/"+year); }}
  • The Student program package Lesson8; public class Student extends Person { private int yearlvl; //constructors public Student(){ super(); yearlvl=1; } public Student(int yearlvl) { super(); if((yearlvl<=4)&&(yearlvl>=1)){ this.yearlvl=yearlvl; } else { this.yearlvl=1; } }
  • The Student program (continued)public Student(String name, int age, Date birthday, intyearlvl){ super(name, age, birthday); if((yearlvl<=4)&&(yearlvl>=1)){ this.yearlvl=yearlvl; } else { this.yearlvl=1; } System.out.print("Hi, "+name+". "); System.out.print(“Your birthday this year is on "); birthday.print_Date(); System.out.println("You are "+age+" years old."); System.out.println(); }
  • The Student program (continued)//accessor methods public void setYearlvl(int yearlvl){ if((yearlvl<=4)&&(yearlvl>=1)){ this.yearlvl=yearlvl; } else { this.yearlvl=1; } } public void setDetails(String name, int age, Date birthday){ super.setDetails(name,age,birthday); System.out.print("Hello, "+name+". "); System.out.print("Your birthday this year is on "); birthday.print_Date(); System.out.println("You are "+age+" years old."); System.out.println(); }
  • The Student program (continued) public void setDetails(String name, int age, Date birthday, intyearlvl){ super.setDetails(name,age,birthday); if((yearlvl<=4)&&(yearlvl>=1)){ this.yearlvl=yearlvl; } else { this.yearlvl=1; } System.out.print("Hello, "+name+". "); System.out.print(" Your birthday this year is on "); birthday.print_Date(); System.out.println("You are "+age+" years old."); System.out.println(); } public int getYearlvl(){ return yearlvl; }}
  • The Teacher programpackage Lesson8;public class Teacher extends Person implements Employee{ private double salary; // constructors public Teacher(){ super(); salary = 4000; } public Teacher(double salary) { super(); this.salary = salary; }
  • The Teacher program (continued)public Teacher(String name, int age, Date birthday, double salary){ super(name, age, birthday); this.salary= salary; System.out.println("Good morning, "+name+". Your salary is "+salary+"."); System.out.println(" Your birthday this year is on "); birthday.print_Date(); System.out.println("You are "+age+" years old."); System.out.println(); } //accessor methods public void setSalary(double salary) { this.salary = salary; }
  • The Teacher program (continued) public void setDetails(String name, int age, Date birthday, double salary){ super.setDetails(name, age, birthday); this.salary = salary; System.out.println("Good afternoon, "+name+". Your salary is "+salary+"."); System.out.println(" Your birthday this year is on "); birthday.print_Date(); System.out.println("You are now "+age+" years old."); System.out.println(); } public double getSalary(){ return salary; }}
  • The Employee programpackage Lesson8;public interface Employee{ public void setSalary(double salary); public void setDetails(String name, int age, Date birthday, double salary); public double getSalary();}
  • Word Bank Superclass Subclass Inheritance Interface Method Signature Overloading Constructor Overriding Method
  • End of Lesson 8 SUMMARY
  • Syntax Review  The constructor of the superclass that has no parameters can be called this way:  super ( );  The constructor of the superclass that has parameters can be called this way:  super (<argument list> );  The syntax to call a method of the superclass is:  super.<method_name> (<argument list> );
  • Syntax ReviewSYNTAX EXAMPLE/S<modifier> class <class_name> public class Student[extends <superclass>] extends Person<modifier> class <name> public class Teacher[extends <superclass>] extends Person[implements <interfaces>] implements Employee
  • Syntax Review (continued) SYNTAX EXAMPLE/S <modifiers> class <class_name>{ public class Person extends Object{ [<attribute_declarations>] //attribute declarations private String name; [<constructor_declarations>] private int age; [<method_declarations>] private Date birthday; } // class constructor public Person() { name = "secret"; age = 0; birthday = new Date(7,7); } //accessor methods - setters public void setName(String X){ name= X; } }
  • Self-check 1I. Use the applications given on our lesson for exercise A and B. A. Supply all the method signatures of Student to the interface Learner, except for the constructors. public interface Learner{ } B. Create a constructor for Person with name and age as parameters. Make sure that you assign values to all the attributes of the class Person.
  • Self-check 2II. Use this diagram in answering the next exercises.
  • Self-checkA. Supply all the method signaturesof Plane to the interfaceFlyingObject, except for theconstructors. public interface FlyingObject{ }
  • End of Lesson LABORATORY EXERCISE
  • Lesson 9 Arrays
  • General Topics • Single-dimensional arrays • Array of Objects • Multidimensional arrays
  • The Single_Array programpublic class Single_Array{ //Constructor for objects of class Single_Array public Single_Array() { } public static void main(String[] args){ int [] GradeLevel=new int [6]; int [] YearLevel={1,2,3,4}; System.out.print("The contents of the YearLevel array: "); print_Single_Array(YearLevel); System.out.print("The contents of the GradeLevel array: "); print_Single_Array(GradeLevel); System.arraycopy(YearLevel,0,GradeLevel,1,YearLevel.length); System.out.print("The contents of the GradeLevel array aftercopying: "); print_Single_Array(GradeLevel); for(int Index=1;Index<GradeLevel.length;Index++){ GradeLevel[Index]=Index*2; } System.out.print("The contents of the GradeLevel array afterassigning values: "); print_Single_Array(GradeLevel); }
  • The Single_Array program (continued) and outputpublic static void print_Single_Array(int[] Array){ for(int subscript=0;subscript<Array.length;subscript++){ System.out.print(Array[subscript]); //prints the arrayelement if((subscript+1)<Array.length){ //prints a comma in-between elements System.out.print(", "); } } System.out.println(); }}
  • Single Dimensional ArraySYNTAX:<data_type> [ ] <array_identifier> = new <data_type>[<no_of_elements>];<data_type> <array_identifier> [ ] = new <data_type>[<no_of_elements>]; Example: First Element Last Element [0] [1] [2] [3] YearLevel 1 2 3 4
  • System.arraycopy SYNTAX: System.arraycopy(<Array_source>, <Array_sourcePosition>, <Array_destination>, <Array_destinationPosition>, <numberOfElements>);
  • The Date programpackage Group.Lesson9.Array_Object;/** * @author Lesley Abe * @version 1 */public class Date{ // instance variables - replace the example below with your own private int day, month, year; //Constructor for objects of class Date with no parameters public Date() { // initialize instance variables day = 1; month=1; year=2005; }//Constructor for objects of class Date with day & month as parameters
  • The Date program (continued)public Date(int this_Day,int this_Month) { // initialise instance variables if((this_Month>=1)&&(this_Month<=12)){ month=this_Month; switch(month){ case 1: case 3: case 5: case 7: case 8: case 10: case 12:if((this_Day>=1)&&(this_Day<=31)){day = this_Day;} else {day=1;} break; case 4: case 6: case 9: case 11:if((this_Day>=1)&&(this_Day<=30)){ day = this_Day;} else {day=1;} break; case 2:if((this_Day>=1)&&(this_Day<=28)){day = this_Day;} else {day=1;} break; } } else { month=1; } year=2005; }
  • The Date program (continued)public static void main(String[] args) { Date[] Birthdays={ new Date(23,10), new Date(22,3) }; Date[] Holidays=new Date[4]; Holidays[0]=new Date(25,12); Holidays[1]=new Date(1,5); Holidays[2]=new Date(1,11); Holidays[3]=new Date(1,1); }}
  • The Two_Dimensional_Array programpublic class Two_Dimensional_Array{ //Constructor for objects of class Two_Dimensional_Array public Two_Dimensional_Array() { } public static void main(String[] args) { final int YearLevel=4; // this is a constant final int Section=2; //this is a constant String TeacherName [] [] = new String [YearLevel] [Section]; String Student [] [] = new String [YearLevel] [ ]; //non-rectangular array //String Student [] [] = new String [] [YearLevel]; //this is illegal! //assign teachers to all the classes in high school TeacherName [0] [0] = "Lesley Abe"; TeacherName [0] [1] = "Arturo Jacinto Jr."; TeacherName [1] [0] = "Olive Hernandez"; TeacherName [1] [1] = "Alvin Ramirez"; TeacherName [2] [0] = "Christopher Ramos"; TeacherName [2] [1] = "Gabriela Alejandra Dans-Lee"; TeacherName [3] [0] = "Joyce Cayamanda"; TeacherName [3] [1] = "Ana Lisa Galinato";
  • The Two_Dimensional_Array program (continued)//indicate how many student assistants per year level Student [0]=new String [2]; Student [1]=new String [2]; Student [2]=new String [1]; Student [3]=new String [1]; //assign student assistants per year level Student [0] [0]= "Stevenson Lee"; Student [0] [1]= "Brian Loya"; Student [1] [0]= "Joselino Luna"; Student [1] [1]= "Allan Valdez"; Student [2] [0]= "John Dionisio"; Student [3] [0]= "Geoffrey Chua"; }}
  • The Two_Dimensional_Array program (continued)public static void main(String[] args) { Date[] Birthdays={ new Date(23,10), newDate(22,3) }; Date[] Holidays=new Date[4]; Holidays[0]=new Date(25,12); Holidays[1]=new Date(1,5); Holidays[2]=new Date(1,11); Holidays[3]=new Date(1,1); }}
  • Multi-Dimensional ArraySYNTAX: <data_type> [ ][ ] <array_identifier> = new <data_type>[<size1>][<size2>]; <data_type> <array_identifier> [ ] [ ] = new <data_type>[<size1>][<size2>];
  • Word Bank
  • End of Lesson 9 SUMMARY
  • Syntax ReviewSYNTAX EXAMPLE/S<data_type> [ ] <array_identifier> = new int [ ] GradeLevel=new int [6];<data_type>[<no_of_elements>];<data_type> < array_identifier> [ ] = new int GradeLevel [ ] =new int [6];<data_type>[<no_of_elements>];<data_type> [ ] < array_identifier> = {< elements int [ ] YearLevel={1,2,3,4};separated by commas>};< array_identifier> [<Index>] = <value>; GradeLevel[Index]=Index*2;<data_type> [ ][ ] <array_identifier> = new String [ ] [ ] TeacherName = new String<data_type>[<size1>][<size2>]; [YearLevel] [ ];<data_type> <array_identifier> [ ] [ ] = new String TeacherName [ ] [ ] = new String<data_type>[<size1>][<size2>]; [YearLevel] [Section];< array_identifier> [<Index1>] [<Index2>] = TeacherName [0] [0] = "Lesley Abe";<value>;System.arraycopy(<Array_source>, System.arraycopy(YearLevel,0,GradeLev<Array_sourcePosition>, <Array_destination>, el,1,YearLevel.length);<Array_destinationPosition>,<numberOfElements>);
  • Self-check 1public class Array1{ //Constructor for objects of class Array1 public Array1() { } public static void main(String[] args){ String [] __________={“Math”,”Science”,_________ }; String [] MyTeachers={______________ }; System.out.print("Here are my subjects: "); print_Array1(MySubjects); System.out.print("My favorite subject is: "+________); System.out.print("My favorite teacher is: "+________); }//method that prints the contents of an array of Stringpublic static void __________(_______[] Array){ for(intsubscript=0;subscript<Array.length;subscript++){//prints the array elementSystem.out.print(__________); if(____________________){//prints a comma in-between elements System.out.print(", "); } } System.out.println(); }}
  • Self-check 2public class Array2{ // Constructor for objects of class Array2 public Array2 (){ } public static void main(String[] args) { final int Row=5; final int Column=5; int [] [] Table=new int [Row][Column]; for(int Row_Ctr=0;Row_Ctr<Row;Row_Ctr++){ for(int Col_Ctr=0;Col_Ctr<Column;Col_Ctr++){ Table[Row_Ctr][Col_Ctr]= Row_Ctr+Col_Ctr; } } }}
  • Self-check 2 (continued) What are the values of the following: Table[0][0]= ___________ Table[2][1]= ___________ Table[1][3]= ___________ Table[4][4]= ___________ Table[3][2]= ___________
  • End of Lesson LABORATORY EXERCISE
  • Lesson 10 GUI
  • General Topics • Abstract Window Toolkit (AWT) - java.awt package - components • Containers • Layout Managers
  • Layout SYNTAX: FlowLayout( ) FlowLayout(int align) FlowLayout(int align, int hgap, int vgap) Examples: setLayout(FlowLayout()); setLayout(FlowLayout(FlowLayout.LEF T)); setLayout(FlowLayout(FlowLayout.RIG HT,23,10));
  • Layout SYNTAX: GridLayout( ); GridLayout(int rows, int cols); GridLayout(int rows, int cols, int hgap, int vgap);Examples:setLayout(GridLayout());SouthPanel.setLayout(new GridLayout(4,3));
  • Layout SYNTAX: BorderLayout( ); Examples: setLayout(new BorderLayout());
  • Sample GUI Project
  • Project Output
  • The DrawTest programpackage Group.Lesson10;import java.awt.event.*;import java.awt.*;public class DrawTest { DrawPanel panel; DrawControls controls; public static void main(String args[]) { Frame Shapes = new Frame("Basic Shapes"); DrawPanel panel = new DrawPanel(); DrawControls controls = new DrawControls(panel); Shapes.add("Center", panel); Shapes.add("West",controls); Shapes.setSize(400,300); Shapes.setVisible(true); Shapes.addWindowListener(new WindowAdapter(){ public void windowClosing(WindowEvent e) { System.exit(0); } } ); }}
  • The DrawPanel programpackage Group.Lesson10;import java.awt.event.*;import java.awt.*;public class DrawPanel extends Panel { public static final int NONE = 0; public static final int RECTANGLE = 1; public static final int CIRCLE = 2; public static final int SQUARE = 3; public static final int TRIANGLE = 4; int mode = NONE; public DrawPanel() { setBackground(Color.white); }
  • The DrawPanel program (continued)public void setDrawMode(int mode) { switch (mode) { case NONE: case RECTANGLE: this.mode = mode; case SQUARE: this.mode = mode; break; case CIRCLE: this.mode = mode; break; case TRIANGLE: this.mode = mode; break; } repaint(); }
  • The DrawPanel program (continued)public void paint(Graphics g) { if (mode == RECTANGLE) { g.fillRect(100, 60, 100,150); } if (mode == CIRCLE) { g.fillOval(100, 90, 100, 100); } if (mode == SQUARE) { g.fillRect(100, 90, 100, 100); } if (mode == TRIANGLE) { int xpoints[] = {90, 150, 210}; int ypoints[] = {90, 200, 90}; int points = 3; g.fillPolygon(xpoints, ypoints, points); } }}
  • Methods Used fillRect(int x, int y, int width, int height) fillOval(int x, int y, int width, int height) fillPolygon(Polygon p)
  • The DrawControl program (continued)package Group.Lesson10;import java.awt.event.*;import java.awt.*;class DrawControls extends Panel implements ItemListener { DrawPanel target; Panel NorthPanel = new Panel(); Panel CenterPanel = new Panel(); Panel SouthPanel = new Panel(); private static int Shape = 0; private static Color targetColor = Color.red; public DrawControls(DrawPanel target) { this.target = target; setLayout(new BorderLayout()); setBackground(Color.lightGray); target.setForeground(Color.red); NorthPanel.setBackground(Color.lightGray ); NorthPanel.setLayout(new GridLayout(6,1));
  • The DrawControl program (continued)add(NorthPanel, BorderLayout.NORTH); CheckboxGroup group = new CheckboxGroup(); Checkbox b; NorthPanel.add(new Label(" Shapes ")); NorthPanel.add(b = new Checkbox("Rectangle", group, false)); b.addItemListener(this); NorthPanel.add(b = new Checkbox("Circle", group, false)); b.addItemListener(this); NorthPanel.add(b = new Checkbox("Square", group, false)); b.addItemListener(this); NorthPanel.add(b = new Checkbox("Triangle", group, false)); b.addItemListener(this);
  • The DrawControl program (continued)CenterPanel.setLayout(new GridLayout(4,1)); add(CenterPanel,BorderLayout.CENTER); CenterPanel.add(new Label(" Colors ")); Choice colors = new Choice(); colors.addItemListener(this); colors.addItem("red"); colors.addItem("green"); colors.addItem("blue"); colors.addItem("pink"); colors.addItem("orange"); colors.addItem("black"); colors.setBackground(Color.white); CenterPanel.add(colors);
  • The DrawControl program (continued) SouthPanel.setLayout(new GridLayout(4,3)); add(SouthPanel, BorderLayout.SOUTH); Button CLEAR = new Button("CLEAR"); Button DRAW = new Button("DRAW"); CLEAR.addMouseListener(new MouseAdapter(){ public void mouseClicked(MouseEvent event){ onCommand(1); } } ); DRAW.addMouseListener(new MouseAdapter(){ public void mouseClicked(MouseEvent event){ onCommand(2); } } ); SouthPanel.add(CLEAR); SouthPanel.add(DRAW);}
  • The DrawControl program (continued)private void onCommand(int btnNUMBER) { switch(btnNUMBER){ case 1: target.setForeground(Color.white); target.setDrawMode(0); break; case 2: target.setForeground(targetColor); target.setDrawMode(Shape); break; } }
  • The DrawControl program (continued)public void itemStateChanged(ItemEvent e) { if (e.getSource() instanceof Checkbox) { Checkbox b = new Checkbox(); b = (Checkbox)e.getSource(); if ( b.getLabel().equals("Rectangle") ){ Shape = 1; } else if ( b.getLabel().equals("Circle") ){ Shape = 2; } else if ( b.getLabel().equals("Square") ){ Shape = 3; } else if ( b.getLabel().equals("Triangle") ){ Shape = 4; } }
  • The DrawControl program (continued)if (e.getSource() instanceof Choice) { String choice = (String) e.getItem(); if (choice.equals("red")) { targetColor=Color.red; } else if (choice.equals("green")) { targetColor=Color.green; } else if (choice.equals("blue")) { targetColor=Color.blue; } else if (choice.equals("pink")) { targetColor=Color.pink; } else if (choice.equals("orange")) { targetColor=Color.orange; } else if (choice.equals("black")) { targetColor=Color.black; } } }}
  • Some Features of AWT • Frames • Checkbox • Checkbox Group: Radio Button • Choice • Button
  • Word Bank • Abstract Class • Component • Frame • Dialog • Panel • Layout Manager
  • End of Lesson 10 SUMMARY
  • Self-checkpackage Lesson10;import java.awt.event.*;import java.awt.*;public class MyPanel{ public static void main(String args[]) { Panel WestPanel = new ________; // initialize the panels Panel CenterPanel = new ________; Panel EastPanel = new ________; Panel MainPanel = new ________; Frame f = new Frame(); WestPanel.setLayout(new ________); // set panel layout ________.____(new Label(" 1 ")); // add item to west panel ________.____(new Label(" 2 ")); ________.____(new Label(" 3 ")); ________.____(new Label(" 4 ")); ________.____(new Label(" 5 ")); ________.____(new Label(" 6 ")); CenterPanel.add(new Label(" 1 ")); CenterPanel.add(new Label(" 2 ")); CenterPanel.add(new Label(" 3 ")); CenterPanel.add(new Label(" 4 ")); CenterPanel.add(new Label(" 5 ")); CenterPanel.add(new Label(" 6 ")); f.add(WestPanel,___________.______); f.add(CenterPanel,BorderLayout.CENTER); f.add(new Label("East"),BorderLayout.EAST); f.add(new Label("North"),BorderLayout.NORTH); f.add(new Label("South"),BorderLayout.SOUTH); f.________(250,250);//set the window size f.________(true); //allows the panel to be visible f._______________(new _____________(){// listen for an event in the window public void windowClosing(WindowEvent e) { System.exit(0); } } ); }}
  • End of Lesson 10 LABORATORY EXERCISE