[Help] Learn How To Create InputDialog

Question

I still learn how to create a component.
I want to create a simple input dialog which modeled after JOptionPane.showInputDialog, but i can't get the value, it's always show null. Anybody know where i doing wrong?
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
public class kotakPesan extends JFrame implements ActionListener {
     String jdlPesan;
     String isiPesan;
     JPanel p = new JPanel();
     JButton bOk = new JButton("Ok");
     JTextField tIsi = new JTextField();
     JLabel lIsi = new JLabel();
     String A;
     public String inputPesan (String Judul, String Isi) {
          this.jdlPesan = Judul;
          this.isiPesan = Isi;
          tampilInputPesan();
          return A;          
     public void tampilInputPesan () {
          setTitle(jdlPesan);
          lIsi.setText(isiPesan);
          p.setLayout(new GridLayout(3, 1));
          p.add(lIsi);
          p.add(tIsi);
          p.add(bOk);
          getContentPane().add(p);
          setDefaultCloseOperation(EXIT_ON_CLOSE);
          pack();
          setVisible(true);
          bOk.addActionListener(this);
     public void actionPerformed (ActionEvent aE) {
          A = tIsi.getText();
}Main Method:
public class Sim {
     public static void main (String[] args) {
          kotakPesan p = new kotakPesan();
          String A = p.inputPesan("Masuk", "Angka");
          System.out.println(A);
}

Answer 1

I'm also learning java and I'm not quite sure what are you trying to do. Are you trying to read your pre-defined input in the text field?
I've created a simple window with a text field, a button and the program will produce a sample output. I hope it will help you a bit.
import javax.swing.*;
import java.awt.event.*;
public class TestWindow extends JFrame
     //Window attributes - references
     private JPanel panel;
     private JLabel inputLabel, outputLabel, resultLabel;
     private JTextField inputField;
     private JButton clickButton;
     //Window size - in pixels
     private final int WINDOW_WIDTH = 300;
     private final int WINDOW_HEIGHT = 450;
     //Constructor
     public TestWindow ()
          setTitle ("This is a simple window.");
          setSize (WINDOW_WIDTH, WINDOW_HEIGHT);
          setDefaultCloseOperation ( JFrame.EXIT_ON_CLOSE );
          createPanel ();
          add (panel);
          setVisible (true);
     private void createPanel ()
          inputLabel = new JLabel ("Enter an integer of your choice: ");
          outputLabel = new JLabel ("Your number is: ");
          resultLabel = new JLabel ("---------------");
          inputField = new JTextField (5);
          clickButton = new JButton (" dum dum dum ");
          clickButton.addActionListener (new TempListener ());
          panel = new JPanel();
          panel.add (inputLabel);
          panel.add (inputField);
          panel.add (outputLabel);
          panel.add (resultLabel);
          panel.add (clickButton);
     //Action listener for the button.
     private class TempListener implements ActionListener
          public void actionPerformed (ActionEvent event)
               int textToInt;
               String inputFieldTempOut = "";
               String text = inputField.getText ();
               textToInt = Integer.parseInt (text);
               if (textToInt % 2 == 0)
                    if (textToInt == 0)
                         inputFieldTempOut = "Neither even nor odd.";
                    else
                         inputFieldTempOut = "An even number.";
               else
                    inputFieldTempOut = "An odd number.";
               resultLabel.setText (inputFieldTempOut);
public class TestWindowDemo
   public static void main(String[] args)
      TestWindow tw = new TestWindow();
}