Hi Friend,

You can use the following code:

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

class Calculate extends JFrame {
 JButton ADD;
 JPanel panel;
 JLabel label1,label2;
 final JTextField   text1,text2;
 int cal;
    Calculate() {
        label1 = new JLabel();
        label1.setText("Enter First Number:");
        text1 = new JTextField(20);

        label2 = new JLabel();
        label2.setText("Enter Second Number:");
        text2 = new JTextField(20);

        ADD=new JButton("Add");


        panel=new JPanel(new GridLayout(3,2));
        panel.add(label1);
        panel.add(text1);
        panel.add(label2);
        panel.add(text2);
        panel.add(ADD);
        add(panel);
        setVisible(true);
        pack();
        setTitle("Calculate");

        ADD.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent ae){
        String value1=text1.getText();
        String value2=text2.getText();
        Pattern p = Pattern.compile("[A-Z,a-z,&%$#@!()*^]");
    Matcher m1 = p.matcher(value1);
    Matcher m2 = p.matcher(value2);
    if(value1.length()==0){
    JOptionPane.showMessageDialog(null,"Enter first number","Error",JOptionPane.ERROR_MESSAGE);
    }
    else if (m1.find()){
    JOptionPane.showMessageDialog(null,"Enter only number!","Error",JOptionPane.ERROR_MESSAGE);
    text1.setText("");
    }
    else if(value2.length()==0){
    JOptionPane.showMessageDialog(null,"Enter second number","Error",JOptionPane.ERROR_MESSAGE);
    }    
    else if (m2.find()){
    JOptionPane.showMessageDialog(null,"Enter only number!","Error",JOptionPane.ERROR_MESSAGE);
    text2.setText("");
    }
    else{
         int n1=Integer.parseInt(value1);
         int n2=Integer.parseInt(value2);
         cal=n1+n2;
         JOptionPane.showMessageDialog(null,"Addition of two numbers is: "+Integer.toString(cal));
        }
       }
    });

}
 public static void main(String arg[]){
    new Calculate();
    }
}

It will be helpful for you. Thanks