PBO (Program Belah Ketupat dengan JAVA)

Hasil yang akan keluar adalah sebagai berikut:

Listing Program

import javax.swing.*;

import java.awt.*;

import java.awt.event.*;

import java.io.*;

class Ketupat extends JFrame implements ActionListener{

                private JTextArea output;

                private JButton btnProses, btnTutup, btnHapus, btnNama;

                private JTextField size;

    public Ketupat(){

                                JPanel panel_1=new JPanel();

                                panel_1.setLayout(new FlowLayout());

                                panel_1.add(btnTutup=new JButton("Exit"));

                                panel_1.add(btnHapus=new JButton("Delete"));

                                panel_1.add(btnNama=new JButton("About Me"));

                                btnTutup.setForeground(Color.blue);

                                btnHapus.setForeground(Color.red);

                                btnNama.setForeground(Color.green);

                                JScrollPane scroll = new JScrollPane(output=new JTextArea());

                output.setFont(new Font("Tahoma",0,14));

                                output.setLineWrap(true);

                                output.setWrapStyleWord(true);

                                scroll.setPreferredSize(new Dimension(500, 500));

                                JPanel panel_2=new JPanel();

                                panel_2.setLayout(new BorderLayout());

                                panel_2.add(scroll);

                output.setEditable(false);

                                JPanel panel_3=new JPanel();

                                panel_3.setLayout(new FlowLayout());

                                panel_3.add(new JLabel("Enter number 0 - 100"));

                                panel_3.add(size=new JTextField(3));

                                panel_3.add(btnProses=new JButton("Print"));

                                setLayout(new BorderLayout());

                                add(panel_2,"Center");

                                add(panel_1,"South");

                                add(panel_3,"North");

                                btnProses.addActionListener(this);

                btnHapus.addActionListener(this);

                                btnTutup.addActionListener(this);

                                btnNama.addActionListener(this);  }

                public void actionPerformed(ActionEvent e){

         String str="";

                   if(e.getSource()==btnProses){                  

                                                  int i,j,k;

                                   try{

                                                   int ukuran=Integer.parseInt(size.getText().trim());

               if((ukuran >= 0)&&(ukuran < 101)){

                  for(i=1;i<=ukuran;i++){

                                                                                  for(j=ukuran;j>=i;j--)

                                                                                                  str+=" ";

                                                                                  for(k=1;k<=i;k++)

                                                                                                  str+="*";

                                                                                                 str+="\n";}

                                                                  for(i=ukuran;i>=1;i--){

                                                                                  for(j=i;j<=ukuran;j++)

                                                                                                  str+=" ";

                      for(k=i;k>=1;k--)

                                                                                                  str+="*";

                                                                                                  str+="\n";           }

                                                       output.setText(str);

                                                }else{

                                  JOptionPane.showMessageDialog(null,"Anda salah input!!!","Warning",

                                  JOptionPane.WARNING_MESSAGE);   }

                                   }catch(Exception ex){

                                                   JOptionPane.showMessageDialog(null,"Error--"+ex.toString(),"Error",

                                                   JOptionPane.ERROR_MESSAGE);}}

                if(e.getSource()==btnTutup){

JOptionPane.showMessageDialog(null,"Bye Bye :D", "Exit", JOptionPane.INFORMATION_MESSAGE);

                                                System.exit(0);}

                if(e.getSource()==btnNama){

                                   JOptionPane.showMessageDialog(null,"nothing spesial", "About Me",              JOptionPane.INFORMATION_MESSAGE);}

                   if(e.getSource()==btnHapus){

                       output.setText(null);

                                   size.setText(null);

                                   str="";}}

    public static void main(String[] args){       

        Ketupat frame = new Ketupat();

                                frame.pack();

                                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

                                frame.setTitle("Program Belah Ketupat");

                                frame.setVisible(true);}}