First Java program

public class MyFirstJavaProgram {

    public static void main(String []args) {
       System.out.println("Hello World");
    }
} 

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);
        }
    }
}