Materi Algo2 SK

/*
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 */
package appsk;

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

/**
 *
 * @author Whoami
 */
public class AppSK extends JFrame implements ActionListener {

    JFrame frame = new JFrame("App SK");
    JTextField tf1 = new JTextField();
    JTextField tf2 = new JTextField();
    JButton btn1 = new JButton("Tambah");
    JButton kurang = new JButton("Kurang");
    JButton btn2 = new JButton("Bagi");
    JButton btn3 = new JButton("Kali");
    JButton cetak = new JButton("Cetak");
    JLabel lb1 = new JLabel("Hasilnya : ");

    public AppSK() {
        tf1.setBounds(50, 10, 400, 30);
        tf2.setBounds(50, 50, 400, 30);
        btn1.setBounds(50, 90, 400, 30);
        kurang.setBounds(50, 130, 400, 30);
        btn2.setBounds(50, 170, 400, 30);
        btn3.setBounds(50, 210, 400, 30);
        lb1.setBounds(50, 250, 400, 30);
        cetak.setBounds(50, 280, 400, 30);

        frame.add(tf1);
        frame.add(tf2);
        frame.add(btn1);
        frame.add(kurang);
        frame.add(lb1);
        frame.add(btn2);
        frame.add(btn3);
        frame.add(cetak);

        kurang.addActionListener(this);
        btn1.addActionListener(this);
        cetak.addActionListener(this);
        btn2.addActionListener(this);
        btn3.addActionListener(this);

        frame.setLayout(null);
        frame.setLocation(300, 100);
        frame.setSize(500, 500);
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        new AppSK();
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        Object objek = e.getSource();
        if (objek == btn1) {
            String angka1 = tf1.getText();
            String angka2 = tf2.getText();
            int hasil = Integer.parseInt(angka1) + Integer.parseInt(angka2);
            lb1.setText("Hasilnya = " + Integer.toString(hasil));
        } else if (objek == kurang) {
            String angka1 = tf1.getText();
            String angka2 = tf2.getText();
            int hasil = Integer.parseInt(angka1) - Integer.parseInt(angka2);
            lb1.setText("Hasilnya = " + Integer.toString(hasil));
        } else if (objek == btn2) {
            String angka1 = tf1.getText();
            String angka2 = tf2.getText();
            int hasil = Integer.parseInt(angka1) / Integer.parseInt(angka2);
            lb1.setText("Hasilnya = " + Integer.toString(hasil));
        } else if (objek == btn3) {
            String angka1 = tf1.getText();
            String angka2 = tf2.getText();
            int hasil = Integer.parseInt(angka1) * Integer.parseInt(angka2);
            lb1.setText("Hasilnya = " + Integer.toString(hasil));
        }else if (objek == cetak) {
            JOptionPane.showMessageDialog(this, lb1.getText());
        }
    }

}