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Loops

Loops:-Loops are used for iterating similar statements for multiple times.
Types:-
1.     For loop
2.     While loop
3.     Do-while loop
4.     For-each loop
For loop:-
Syntax of for loop:-
for(initialization;condition;counter)
Statement1;
for(initialization;condition;counter)
{
Statement1;
Statement1;
}
For loop must contain two semicolons inside parenthesis. for loop contains three parts inside parenthesis first part contain initialization ,second part contain condition and third part contain counterpart. control first go for initialization then go for condition if the given condition is true then go for body execution after that control go for counter then again go for condition if condition is true then repeated and so on.  
Example1:-TestLoop.java
class TestLoop
{
public static void main(String[]args)
{
int i;
System.out.println("Demo of for loop");
for(i=1;i<=10;i++)
System.out.println("i :"+i);
}
}
Output:-it will print 1 to 10.

Example2:-TestLoop.java
class TestLoop
{
public static void main(String[]args)
{
int i;
System.out.println("Demo of for loop");
for(i=1;i<=10;++i)
System.out.println("i :"+i);
}
}
Output:-it will print 1 to 10.
Example3:-TestLoop.java
class TestLoop
{
public static void main(String[]args)
{
System.out.println("Demo of for loop");
int i=1;
for(;i<=10;)
System.out.println("i :"+(i++));
}
}
Output:-Output:-it will print 1 to 10.
Example4:-TestLoop.java
class TestLoop
{
public static void main(String[]args)
{
System.out.println("Demo of for loop");
for(int i=1;i<=10;i++)
{
System.out.println("i :"+i);
}
}
}
Output:-print 1 to 10.
Example5:-
class TestLoop
{
public static void main(String[]args)
{
System.out.println("Demo of for loop");
for(int i=1;i<=10;i++)
{
if(i%2==0)
System.out.println("i :"+i);
}
}
}
Output:-all even number between 1 to 10

While Loop:-while loop is very similar to for loop.
Syntax:-            
Initialization;
While(condition)
{
Statements;
Counter;
}
Loop will execute if condition is true.

Example1:-TestLoop.java
class TestLoop
{
public static void main(String[]args)
{
System.out.println("Demo of while loop");
int i=1;
while(i<=10)
System.out.println("i :"+(i++));
}
}
Output:-print 1 to 10.
Example2:-TestLoop.java
class TestLoop
{
public static void main(String[]args)
{
System.out.println("Demo of while loop");
int i=1;
while(i<=10)
{
System.out.println("i :"+i);
i++;//++i output will be same
}
}
}
Output:-print 1 to 10.
Example3:-TestLoop.java
class TestLoop
{
public static void main(String[]args)
{
System.out.println("Demo of while loop");
int i=1;
while(i<=10)
{
if(i%2!=0)
System.out.println("i :"+i);
i++;//++i output will be same
}
}
}
Output:-print odd number b/w 1 to 10.

do-while loop:-do while loop is different from for and while loop, both for and while loop are entry controlled where do-while loop is exit controlled loop that means loop can execute once if condition is false.
Syntax:-
Initialization;
do
{
Statements;
Counter;
}while(condition);

Example1:-TestLoop.java
class TestLoop
{
public static void main(String[]args)
{
System.out.println("Demo of do-while loop");
int i=1;
do
{
System.out.println("i :"+i);
i++;//++i output will be same
}while(i<=10);
}
}
Output:-print 1 to 10.
Example2:-TestLoop.java
class TestLoop
{
public static void main(String[]args)
{
System.out.println("Demo of do-while loop");
int i=1;
do
{
if(i%2==0)
System.out.println("i :"+i);
i++;//++i output will be same
}while(i<=10);
}
}

Output:-print even number b/w 1 to 10.
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