This document discusses various Java programming concepts including type casting, primitive type conversion, logical operators, enhanced for loops, controlling statements like break and continue, variable scope, and assertions. It provides examples to illustrate type casting rules, primitive type conversion precision and requirements for explicit casting, the difference between the && and & logical operators, how to use enhanced for loops to iterate over arrays, examples of labeled and unlabeled break and continue statements, variable scope rules, and how to use assertion statements to test assumptions.

1. Core Java
Debasish Pratihari
Type Casting:


Converting one type of data into another must
follow the rules of casting. If a conversion
results in the loss of precision, as in an int
value converted to a short, then the compiler
will issue an error message unless an explicit
cast is made.
a data type with lower precision (fewer bits)
can be converted to a type of higher precision
without explicit casting. To convert a higher
precision type to a lower precision, however,
an explicit cast is required or the compiler will
flag an error.
Primitive Type Conversion Table:
Note :




The symbol C indicates that an explicit
cast is required since the precision is
decreasing.
The symbol A indicates that the precision
is increasing so an automatic cast occurs
without the need for an explicit cast.
N indicates that the conversion is not
allowed.
The * asterisk indicates that the least
significant digits may be lost in the
conversion.
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2. Core Java
Debasish Pratihari
&& verses & :

The && operators perform Conditional-AND
operations on two Boolean expressions. These
operators exhibit "short-circuiting" behavior,
which means that the second operand is
evaluated only if needed.

The & operator do the same thing as && but it
does not exhibit "short-circuiting" behavior,
which means that the both operand are
evaluated always.
Enhanced for loop :
Example:1
class LoopDemo{
public static void main(String[] args){
int[] numbers = {1,2,3,4,5,6,7,8,9,10};
for (int item : numbers) {
System.out.println("Count is: " + item);
}
}
}
Example:2
class LoopDemo2{
public static void main(String[] args){
String [] names = {"Debasish","Sushant","Sidharth",
"Sanat","Nayaran"};
for (String name : names) {
System.out.println("Mr. " + name);
}
}
}
Controlling Statement in Java :



The break Statement
o Un-labeled
o Labeled
The continue Statement
o Un-labeled
o Labeled
The return Statement
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3. Core Java
Debasish Pratihari
Example of Un-labeled break :
class BreakTest{
public static void main(String args[]){
for( int i=1;i<=5;i++){
System.out.println("Outer loop"+i);
for(int j=10;j<=15;j++){
if(j==12)
break ;
System.out.println("Inner Loop"+j);
}
}
}
}
Example of Labeled break :
class BreakTest{
public static void main(String args[]){
stop:
for( int i=1;i<=5;i++){
System.out.println("Outer loop"+i);
for(int j=10;j<=15;j++){
if(j= =12)
break stop;
System.out.println("Inner Loop"+j);
}
}
}
}
Example of Un-labeled continue :
class ContinueTest{
public static void main(String args[]){
for( int i=1;i<=5;i++){
System.out.println("Outer loop"+i);
for(int j=10;j<=15;j++){
if(j= =12)
continue ;
System.out.println("Inner Loop"+j);
}
}
}
}
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4. Core Java
Debasish Pratihari
Example of labeled continue :
class ContinueTest{
public static void main(String args[]){
stop:
for( int i=1;i<=5;i++){
System.out.println("Outer loop"+i);
for(int j=10;j<=15;j++){
if(j==12)
continue stop;
System.out.println("Inner Loop"+j);
}
}
}
}
Variable Scope :
25% 
The Scope of a variable is the part of the program
over which the variable name can be referenced.
class x{
public static void main(String args[]){
int i;
{
int j;
//referring to i and j is ok here
}
//referring to i ok here
//referring to j is not ok here
}
}
Assertion :

An assertion is a statement in the JavaTM
programming language that enables you to test your
assumptions about your program.

Each assertion contains a boolean expression that
you believe will be true when the assertion executes.
If it is not true, the system will throw an error.

The assertion statement has two forms.
o assert Expression1 ;
o assert Expression1 : Expression2 ;
To activate assertions:
o java –ea Test

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