Sum of two Numbers

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;

class SumOfNumbers extends JFrame
{
    SumOfNumbers(){
    JLabel lab1=new JLabel("Enter first number: ");
    final JTextField text1=new JTextField(20);

    JLabel lab2=new JLabel("Enter second number: ");
    final JTextField text2=new JTextField(20);

    JButton b=new JButton("Sum");
    b.addActionListener(new ActionListener(){
        public void actionPerformed(ActionEvent e){
         int num1=Integer.parseInt(text1.getText());
         int num2=Integer.parseInt(text1.getText());
         int sum=num1+num2;
         JOptionPane.showMessageDialog(null,Integer.toString(sum));

        }
    });
    JPanel p=new JPanel(new GridLayout(3,2));
    p.add(lab1);
    p.add(text1);
    p.add(lab2);
    p.add(text2);
    p.add(b);
    add(p);
    setVisible(true);
    setSize(300,100);
    }
    public static void main(String[] args) 
    {
        new SumOfNumbers();
    }
}

Surface Area of Sphere:

import java.util.*;
class SurfaceAreaOfSphere 
{
   public static void main(String[] args) 
    {
        Scanner input=new Scanner(System.in);
        System.out.print("Enter radius: ");
        double r =input.nextDouble();
        double sarea = 4 * Math.PI * r*r;
        System.out.println("Surface area: "+sarea);
    }
}