Java Switch Statement

Syntax:

switch(expression){    

   case value1:    

      //code to be executed;    

      break;  //optional  

   case value2:    

      //code to be executed;    

      break;  //optional  

   ......    

   default:     

      //code to be executed if all cases are not matched;    

}

public class SwitchExample {  

   public static void main(String[] args) {  

      int number=20;  

      switch(number){  

         case 10: 

            System.out.println("10");

            break;  

         case 20: 

            System.out.println("20");

            break;  

         case 30: 

            System.out.println("30");

            break;  

         default:

            System.out.println("Not in 10, 20 or 30");  

      }  

   }  

}  

--------------------------------------------

Output:

20

public class SwitchExample2 {  

   public static void main(String[] args) {  

      int number=20;  

      switch(number){  

         case 10: 

            System.out.println("10");  

         case 20: 

            System.out.println("20");  

         case 30: 

            System.out.println("30");  

         default:

            System.out.println("Not in 10, 20 or 30");  

      }  

   }  

}

--------------------------------------------

Output:

20

30

Not in 10, 20 or 30

Java For Loop

Java Simple For Loop

Syntax:

for(initialization;condition;incr/decr){  

   //code to be executed  

}

public class ForExample {  

   public static void main(String[] args) {  

      for(int i=1;i<=10;i++){  

         System.out.println(i);  

      }  

   }  

}

--------------------------------------------

Output:

1

2

3

4

5

6

7

8

9

10

Infinitive For Loop

public class ForExample {  

   public static void main(String[] args) {  

      for(;;){  

         System.out.println("infinitive loop");  

      }  

   }  

}

--------------------------------------------

Output:

infinitive loop

infinitive loop

infinitive loop

infinitive loop

infinitive loop

ctrl+c

Java For-each Loop

Syntax:

for(Type var:array){  

   //code to be executed  

}

public class ForEachExample {  

   public static void main(String[] args) {  

      int arr[]={12,23,44,56,78};  

      for(int i:arr){  

         System.out.println(i);  

      }  

   }  

}

--------------------------------------------

Output:

12

23

44

56

78

Java While Loop

Syntax:

while(condition){  
   //code to be executed  
}

public class WhileExample {  

   public static void main(String[] args) {  

      int i=1;  

      while(i<=10){  

         System.out.println(i++);    

      }  

   }  

}

--------------------------------------------

Output:

1

2

3

4

5

6

7

8

9

10

Java Infinitive While Loop

public class WhileExample2 {  

   public static void main(String[] args) {  

      while(true){  

         System.out.println("infinitive while loop");  

      }  

   }  

}

--------------------------------------------

Output:

infinitive while loop

infinitive while loop

infinitive while loop

infinitive while loop

infinitive while loop

ctrl+c

Java do-while Loop

do{  

   //code to be executed  

} while (condition);

public class DoWhileExample {  

   public static void main(String[] args) {  

      int i=1;  

      do{  

         System.out.println(i++);  

      }while(i<=10);  

   }  

}

--------------------------------------------

Output:

1

2

3

4

5

6

7

8

9

10

Java Infinitive do-while Loop

public class DoWhileExample2 {  
   public static void main(String[] args) {  
      do{  
         System.out.println("infinitive do while loop");  
      }while(true);  
   }  
}  

--------------------------------------------

Output:

infinitive do while loop
infinitive do while loop
infinitive do while loop
ctrl+c

Java Break Statement

Java Break Statement with Loop

public class BreakExample {  

   public static void main(String[] args) {  

      for(int i=1;i<=10;i++){  

         if(i==5){  

            break;  

         }  

         System.out.println(i);  

      }  

   }  

}

--------------------------------------------

Output:

1

2

3

4

Java Break Statement with Inner Loop

public class BreakExample2 {  

   public static void main(String[] args) {  

      for(int i=1;i<=3;i++){    

         for(int j=1;j<=3;j++){    

            if(i==2&&j==2){    

               break;    

            }    

            System.out.println("In i="+i+" j="+j);    

         }    

         System.out.println("Out i="+i);    

      }    

   }  

}

--------------------------------------------

Output:

In i=1 j=1

In i=1 j=2

In i=1 j=3

Out i=1

In i=2 j=1

Out i=2

In i=3 j=1

In i=3 j=2

In i=3 j=3

Out i=3

Java Continue Statement

public class ContinueExample {  

   public static void main(String[] args) {  

      for(int i=1;i<=10;i++){  

         if(i==5){  

            continue;  

         }  

         System.out.println(i);  

      }  

   }  

}

--------------------------------------------

Output:

1

2

3

4

6

7

8

9

10

Java Continue Statement with Inner Loop

public class ContinueExample2 {  

   public static void main(String[] args) {  

      for(int i=1;i<=3;i++){    

         for(int j=1;j<=3;j++){    

            if(i==2&&j==2){    

               continue;    

            }    

            System.out.println("In i="+i+" j="+j);    

         }    

         System.out.println("Out i="+i);    

      }    

   }  

}

--------------------------------------------

Output:

In i=1 j=1
In i=1 j=2
In i=1 j=3
Out i=1
In i=2 j=1
In i=2 j=3
Out i=2
In i=3 j=1
In i=3 j=2
In i=3 j=3
Out i=3

Java Comments

1) Java Single Line Comment

//This is single line comment

2) Java Multi Line Comment

/* 

This  

is  

multi line  

comment 

*/

3) Java Documentation Comment

/** 

This  

is  

documentation  

comment 

*/

/** The Calculator class provides methods to get addition and subtraction of given 2 numbers.*/  

   public class Calculator {  

   /** The add() method returns addition of given numbers.*/  

   public static int add(int a, int b){return a+b;}  

   /** The sub() method returns subtraction of given numbers.*/  

   public static int sub(int a, int b){return a-b;}  

}

javac Calculator.java

javadoc Calculator.java