import java.util.*;

public class Calculate {

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Num1: ");
        int num1 = input.nextInt();
        System.out.print("Num2: ");
        int num2 = input.nextInt();
        if (num1 > 0 && num2 > 0) {
            int sum = num1 + num2;
            System.out.println("Sum= " + sum);
        }
            else {
            System.out.println("Invalid Numbers");
            System.out.println("End of program");
        }
    }
}

with java

Write a program to get student grade for 3 different subjects, and display the CGPA for them.

Write a program to read 8 integer numbers from user, put them into 2 matrix A and B(2 by 2), and multiply the matrix and display the result.

import java.util.Scanner //Console input rather than JPanes

{

       public static void main(String[] args)
       {
                 Scanner x = new Scanner(System.in);
                 System.out.println("Enter number 1 ");
                 int first = x.nextInt();
                 System.out.println("Enter number 2 ");
                 int second = x.nextInt(); 
                 System.out.println("Enter number 3 ");
                 int third = x.nextInt();
               double GPA = (first + second + third / 3) / 20 ;
                 GPA--; //Equal to GPA = GPA - 1; 
                 System.out.print(GPA);
         }                                                      }