Hi Friend,

Try the following code:

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

class Form extends JFrame {
JButton ADD,SUB,MUL,DIV;
JPanel panel1,panel2;
JLabel label1,label2,label3;
final JTextField text1,text2,text3;
int cal;
Form() {
label1 = new JLabel();
label1.setText("Enter First Number:");
text1 = new JTextField(20);
label2 = new JLabel();
label2.setText("Enter Second Number:");
text2 = new JTextField(20);
label3 = new JLabel("Result");
text3 = new JTextField(20);
text3.setText("");
ADD=new JButton("+");
SUB=new JButton("-");
MUL=new JButton("*");
DIV=new JButton("/");
panel1=new JPanel(new GridLayout(3,2));
panel2=new JPanel(new GridLayout(1,4));
panel1.add(label1);
panel1.add(text1);
panel1.add(label2);
panel1.add(text2);
panel1.add(label3);
panel1.add(text3);
panel2.add(ADD);
panel2.add(SUB);
panel2.add(MUL);
panel2.add(DIV);
add(panel1,BorderLayout.NORTH);
add(panel2,BorderLayout.CENTER);
setTitle("Calculate");
ADD.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae){
String value1=text1.getText();
String value2=text2.getText();
String expression = "^[-+]?[0-9]*\\.?[0-9]+$";
CharSequence inputStr1 = value1;
CharSequence inputStr2 = value2;

Pattern pattern = Pattern.compile(expression);
Matcher matcher = pattern.matcher(inputStr1);
Matcher matcher1 = pattern.matcher(inputStr2);
if((matcher.matches())&&(matcher1.matches())){
int n1=Integer.parseInt(value1);
int n2=Integer.parseInt(value2);
cal=n1+n2;
System.out.println(cal);
String res=Integer.toString(cal);
text3.setText(res);
}
else{
JOptionPane.showMessageDialog(null, "Please enter only numbers", "Error", JOptionPane.ERROR_MESSAGE);
}
}
});

continue.........

SUB.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae){
String value1=text1.getText();
String value2=text2.getText();
String expression = "^[-+]?[0-9]*\\.?[0-9]+$";
CharSequence inputStr1 = value1;
CharSequence inputStr2 = value2;

Pattern pattern = Pattern.compile(expression);
Matcher matcher = pattern.matcher(inputStr1);
Matcher matcher1 = pattern.matcher(inputStr2);
if((matcher.matches())&&(matcher1.matches())){
int n1=Integer.parseInt(value1);
int n2=Integer.parseInt(value2);
cal=n1-n2;
System.out.println(cal);
String res=Integer.toString(cal);
text3.setText(res);
}
else{
JOptionPane.showMessageDialog(null, "Please enter only numbers", "Error", JOptionPane.ERROR_MESSAGE);
}
}
});
MUL.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae){
String value1=text1.getText();
String value2=text2.getText();
String expression = "^[-+]?[0-9]*\\.?[0-9]+$";
CharSequence inputStr1 = value1;
CharSequence inputStr2 = value2;

Pattern pattern = Pattern.compile(expression);
Matcher matcher = pattern.matcher(inputStr1);
Matcher matcher1 = pattern.matcher(inputStr2);
if((matcher.matches())&&(matcher1.matches())){
int n1=Integer.parseInt(value1);
int n2=Integer.parseInt(value2);
cal=n1*n2;
System.out.println(cal);
String res=Integer.toString(cal);
text3.setText(res);
}
else{
JOptionPane.showMessageDialog(null, "Please enter only numbers", "Error", JOptionPane.ERROR_MESSAGE);
}
}
});
DIV.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae){
String value1=text1.getText();
String value2=text2.getText();
String expression = "^[-+]?[0-9]*\\.?[0-9]+$";
CharSequence inputStr1 = value1;
CharSequence inputStr2 = value2;

Pattern pattern = Pattern.compile(expression);
Matcher matcher = pattern.matcher(inputStr1);
Matcher matcher1 = pattern.matcher(inputStr2);
if((matcher.matches())&&(matcher1.matches())){
int n1=Integer.parseInt(value1);
int n2=Integer.parseInt(value2);
cal=n1/n2;
System.out.println(cal);
String res=Integer.toString(cal);
text3.setText(res);
}
else{
JOptionPane.showMessageDialog(null, "Please enter only numbers", "Error", JOptionPane.ERROR_MESSAGE);
}
}
});
text1.addKeyListener(new KeyAdapter() {
public void keyPressed(KeyEvent e) {
text2.setText("");
text3.setText("");
}
});


}
}
class ArithmeticOperations
{
public static void main(String arg[])
{
try
{
Form frame=new Form();

frame.setSize(300,120);
frame.setVisible(true);
}
catch(Exception e)
{}
}
}
Thanks