There may be a situation when we need to execute a block of code several number of times, and is often referred to as a loop. Java has very flexible three looping mechanisms.

1. While Loop

A while loop is a control structure that allows you to repeat a task a certain number of times.

Syntax:

while(Boolean_expression) {
//Statements
}

When executing, if the boolean expression result is true then the actions inside the loop will be executed. This will continue as long as the expression result is true.

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public class ForLoopExample {
public static void main(String args[]) {
int a = 1;
while( a < 10 ) {
System.out.println("value of a : " + a );
a++;
}
}
}
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2. Do-While Loop

The DO … WHILE loop is almost similar to the WHILE loop, the difference is that in this loop, the execution of statements occur before checking of a condition.

Syntax:

do {
//Statements
}while(Boolean_expression);

do…while loop checks the value of the loop control variable at the bottom of the loop after one repetition has occurred.

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public class DoWhileLoop {
public static void main(String[] args) {
int i =10;
do{
i=i+10;
System.out.println("Loop Counter Variable=" +i);
}while (i<10);
}
}
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3. For Loop

For Loop checks the condition and executes the set of the statements , It is loop control statement in java. It contain the following statements such as “Initialization” , “Condition” and “Increment/Decrement” statement

Syntax:
for(initialization; Condition; update)
{
//Statements
}

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public class ForLoopExample{
public static void main(String args[])
{
for(int i=0;i<10;i++)
{
System.out.println("Hello");
}
}
}
[/php]

Download Code Here