// importing necessary libraries
import java.awt.*;
import java.awt.event.*;
// Our class extends Frame class and implements ActionListener interface
public class Program2 extends Frame implements ActionListener {
 // creating instances of TextField and Button class
 TextField tf1, tf2, tf3;
 Button b1, b2;
 // instantiating using constructor
 Program2() {
 // instantiating objects of text field and button
 // setting position of components in frame
 tf1 = new TextField();
 tf1.setBounds(50, 50, 150, 20);
 tf2 = new TextField();
 tf2.setBounds(50, 100, 150, 20);
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 tf3 = new TextField();
 tf3.setBounds(50, 150, 150, 20);
 tf3.setEditable(false);
 b1 = new Button("+");
 b1.setBounds(50, 200, 50, 50);
 b2 = new Button("-");
 b2.setBounds(120,200,50,50);
 // adding action listener
 b1.addActionListener(this);
 b2.addActionListener(this);
 // adding components to frame
 add(tf1);
 add(tf2);
 add(tf3);
 add(b1);
 add(b2);
 // setting size, layout and visibility of frame
 setSize(300,300);
 setLayout(null);
 setVisible(true);
 }
 // defining the actionPerformed method to generate an event on buttons
 public void actionPerformed(ActionEvent e) {
 String s1 = tf1.getText();
 String s2 = tf2.getText();
 int a = Integer.parseInt(s1);
 int b = Integer.parseInt(s2);
 int c = 0;
 if (e.getSource() == b1){
 c = a + b;
 }
 else if (e.getSource() == b2){
 c = a - b;
 }
 String result = String.valueOf(c);
 tf3.setText(result);
 }
// main method
public static void main(String[] args) {
 new Program2();
}
}