Loops in Java

Loops in Java is use to execute a group of instructions or a block of code multiple times, without writing it repeatedly. The block of code is execute based on a certain condition.

Types of Loops in Java

Java While Loop

A while loop statement repeatedly executes a target statement as long as a given condition is true is knows as While Loop.

Flowchart

Syntax

while (condition){    
//code to be executed   
increment / decrement statement  
}    

Syntax of Java While Loop

Example of while loop

Input Value

public class loopw {
    public static void main(String[] args) {  
        int a=0;  
        while(a<=5){  
            System.out.println(a);  
        a++;  
        }  
    }  
}

Java While Loop

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Output Value

For loop in Java

For loop is the the most common use loop. It is use when we want to perform initialization, condition and increment or decrement Operation in single line.

Flowchart

Syntax

for (initialization condition; testing condition;increment/decrement)
{
    statement(s)
}

Syntax of For loop in Java

Example of For loop in Java

Input Value

public class loopw {
    public static void main(String[] args) {  
        for (int a=11;a<=15;a++)
       {
         System.out.println(a);
       } 
    }  
}

For loop in Java

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Output Value

Do While loop in Java

Do While loop is a post test loop. It is use when we want to execute loop body atleast once even condition is false. It is also knows as Exit control Loop.

Syntax

do{    
//code to be executed / loop body  
//update statement   
}while (condition); 

Syntax of Do While loop in Java

Flowchart

Example of Do While loop in Java

Input Value

public class loopw {
    public static void main(String[] args) {  
        int a=11;    
    do{    
        System.out.println(a);    
    a++;    
    }while(a<=15);    
    }  
}

Do While loop in Java

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Output Value

Enhanced for loop in Java

This feature is also include in java version 5 and later. This is special kind of for loop that can be use to access the elements of a list without giving their index number. It means it always access elements of list from start to end. It is advantageous over for loop in respect of list because it fallows two parameters only. Enhanced for loop does not replace for loop.

Syntax

for(declaration : expression) {
   // Statements
}

Syntax of Enhanced for loop in Java

Example of Enhanced for loop in Java

Input Value

public class loopw {
    public static void main(String[] args) {  
        int [] marks = {55,66,65,57,62};

      for(int a : marks ) {
         System.out.print( a );
         System.out.print(",");
      }
      System.out.print("\n");
      String [] Subject = {"HTML", "CSS", "JAVA", "c", "C++"};

      for( String subject : Subject ) {
         System.out.print( subject );
         System.out.print(",");
      }  
    }  
}

Enhanced for loop in Java

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Output Value

Labelled for loop in Java

Label is the mark in program that can be use for sending the execution control to that level.

Syntax

labelname:    
for(initialization; condition; incr/decr)  
{    
//functionality of the loop    
}    

Syntax of Labelled for loop in Java

Example of Labelled for loop in Java

Input Value

public class loopw {
public static void main(String[] args)
{	
 outer: for(int i = 2; i < 5; i++)
 {
  System.out.println(i);	 
 for(int j = 2; j < 4; j++)
 {
  System.out.println(j);
  if(i == j)
    continue outer;  
  }
 }
}}

Labelled for loop in Java

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Output Value

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