java program for addition, subtraction, multiplication and division

import java.io.*;
class allprograms
{
    public static void main(String args[])
    {
        try
        {
            int a,b,c,d,e;
            DataInputStream cin=new DataInputStream(System.in);
            System.out.println("Enter the first number");
            a=Integer.parseInt(cin.readLine());
            System.out.println("Enter the Second number");
            b=Integer.parseInt(cin.readLine());
            c=a+b;
            d=a-b;
            e=a*b;
            float f=b/a;
            System.out.println(a+" + "+b+" = "+c);
            System.out.println(a+" - "+b+" = "+d);
            System.out.println(a+" * "+b+" = "+e);
            System.out.println(b+" / "+a+" = "+f);
        }
        catch(Exception e)
        {
            System.out.println(e);
        }
    }
}

Demonstration of switch statement in java

public class Test {

   public static void main(String args[]){
      char grade = args[0].charAt(0);

      switch(grade)
      {
         case 'A' :
            System.out.println("Excellent!"); 
            break;
         case 'B' :
         case 'C' :
            System.out.println("Well done");
            break;
         case 'D' :
            System.out.println("You passed");
         case 'F' :
            System.out.println("Better try again");
            break;
         default :
            System.out.println("Invalid grade");
      }
      System.out.println("Your grade is " + grade);
   }
}

Demonstration of if -else statement

public class Test {

   public static void main(String args[]){
      int x = 30;

      if( x < 20 ){
         System.out.print("This is if statement");
      }else{
         System.out.print("This is else statement");
      }
   }
}

Demonstration of Nested if in Java

public class Test {

   public static void main(String args[]){
      int x = 30;
      int y = 10;

      if( x == 30 ){
         if( y == 10 ){
         System.out.print("X = 30 and Y = 10");
      }
   }
}

Java program for if-else if OR if-else if program in java

public class Test {

   public static void main(String args[]){
      int x = 30;

      if( x == 10 ){
         System.out.print("Value of X is 10");
      }else if( x == 20 ){
         System.out.print("Value of X is 20");
      }else if( x == 30 ){
         System.out.print("Value of X is 30");
      }else{
         System.out.print("This is else statement");
      }
   }
}

program for if statement OR use of if statement in java

public class Test {

   public static void main(String args[]){
      int x = 10;

      if( x < 20 ){
         System.out.print("This is if statement");
      }
   }
}

Demonstration for continue keyword

public class Test {

   public static void main(String args[]) {
      int [] numbers = {10, 20, 30, 40, 50};

      for(int x : numbers ) {
         if( x == 30 ) {
       continue;
         }
         System.out.print( x );
         System.out.print("\n");
      }
   }
}