Java Tut – Loop

Java programming language provides the following types of loop to handle looping requirements.Click on the following links to check the detail.
While Loop:
Syntax for while loop:

while(Boolean_expression)
{
//Statements
}

e.g:

public class While{
public static void main(String[] args)
{
int x=10;
while(x<20)
{
System.out.print("value of x: "+x);
x++;
System.out.print("\n");
}
}
}

output:

value of x: 10
value of x: 11
value of x: 12
value of x: 13
value of x: 14
value of x: 15
value of x: 16
value of x: 17
value of x: 18
value of x: 19

For Loop:
Syntax for for loop is:
for(iitialization;Boolean_expression;update)
{
//statements
}
the update statement can be left blank with a semicolon at the end.
example :

public class For {
public static void main(String[] args)
{
	for(int x=10;x<20;x=x+1){
		System.out.print("Value of x is: "+x);
		System.out.print("\n");
	}
	
}
}

out:

Value of x is: 10
Value of x is: 11
Value of x is: 12
Value of x is: 13
Value of x is: 14
Value of x is: 15
Value of x is: 16
Value of x is: 17
Value of x is: 18
Value of x is: 19

do..while loop:
do{
//Statements
}while(boolean_expression)

e.g:

public class DoWhile {
public static void main(String[] args)
{
	int a=10;
	do{
		System.out.print("Value of a :"+a);
		a++;
		System.out.print("\n");
	}while(a<20);
}
}

output:

Value of a :10
Value of a :11
Value of a :12
Value of a :13
Value of a :14
Value of a :15
Value of a :16
Value of a :17
Value of a :18
Value of a :19

 

Loop Control Statements:
break statements:
example:

public class Break {
public static void main(String[] args)
{
	int[] numbers={10,20,30,40,50,60};
	for(int x:numbers){
		if(x==40){
			break;
}
		System.out.print(x);
		System.out.print("\n");
}
}
}

output:

10
20
30

continue statements:

– In a for loop, the continue keyword causes control to immediately jump to the update statement.

– In a while loop or do-while loop, control immediately jumps to the boolean expression.

public class Continue {

	public static void main(String[] args)
	{
		int[] numbers={10,20,30,40,50,60};
		for(int x:numbers)
		{
			if(x==30)
			{
				continue;
			}
			System.out.print(x);
			System.out.print("\n");
		}
	}
	
}

output:

10
20
40
50
60

 

Enhanced for loop in Java:
it included from Java 5, the enhanced for loop was introduced.This is mainly used to traverse collection of elements including arrays.
Syntax:

for(declaration:expression)
{
//statements
}

Declaration: The newly declared block variable, which is a type compatible with the elements of the array you are accessing.

Expression: This evaluates to the array you need to loop through.The expression can be an array variable or method call that returns an array.
e.g:

public class Enhanced {
public static void main(String[] args)
{
	int[] numbers={10,20,30,40,50};
	for(int x:numbers)
	{
		System.out.println( x );
		System.out.println(",");
	}
	System.out.println("\n");
	String[] names={"James","Larry","Tom","Lacy"};
	for(String nameu:names)
	{
		System.out.println(nameu);
		System.out.println(",");
	}
}
}

output:

10
,
20
,
30
,
40
,
50
,


James
,
Larry
,
Tom
,
Lacy
,

 

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Author: zakilive

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