JTextField setText（）方法在run（）方法中不起作用

Question

I'm having trouble with the setText() method of the JTextField class. In short, it doesn't work in the CounterPanel class below. It is called in the run() method and it does not update the text field. The rest of the code is run (it can be printed to console using the println() statements that I've left in.

These panels are added to the MainWindow class that I've also included below. There are 4 CounterPanels in MainWindow and each gets its own thread. As I've said, the rest of the code in the run() method works OK, so can anyone tell me where I'm going wrong?

Many thanks.

import java.awt.Color;

import javax.swing.BorderFactory;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;

import net.miginfocom.swing.MigLayout;

public class CounterPanel extends JPanel implements Runnable {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    private JLabel labelOne = new JLabel("Counter 1");
    private JTextField textFieldOne = new JTextField(3);
    private JLabel labelTwo = new JLabel("Counter 2");
    private JTextField textFieldTwo = new JTextField(3);

    private int counter;
    private String counterAsString = Integer.toString(counter);

    public CounterPanel() {
        this.setLayout(new MigLayout());
        this.setBorder(BorderFactory.createLineBorder(Color.black, 1));
        this.add(labelOne);
        this.add(textFieldOne);
        this.add(labelTwo);
        this.add(textFieldTwo);
    }

    @Override
    public void run() {
        while(counter < 100) {
            textFieldOne.setText(counterAsString);
            textFieldTwo.setText(counterAsString);
            System.out.println("Counter 1 = " + counterAsString + ", Counter 2 = " + counterAsString);
            counter++;
        }
        System.out.println("FINISHED");
    }

}




import java.awt.Color;

import javax.swing.*;

import net.miginfocom.swing.MigLayout;

public class MainWindow extends JFrame {

    private CounterPanel panel1 = new CounterPanel();
    private CounterPanel panel2 = new CounterPanel();
    private CounterPanel panel3 = new CounterPanel();
    private CounterPanel panel4 = new CounterPanel();

    private JLabel labelOne = new JLabel("A");
    private JLabel labelTwo = new JLabel("B");
    private JLabel labelThree = new JLabel("C");
    private JLabel labelFour = new JLabel("D");


    public MainWindow() {
        this.setDefaultCloseOperation(EXIT_ON_CLOSE);
        this.setLayout(new MigLayout());
        this.add(labelOne, "gapright 20px");
        this.getContentPane().add(panel1, "wrap");
        this.add(labelTwo);
        this.getContentPane().add(panel2, "wrap");
        this.add(labelThree);
        this.getContentPane().add(panel3, "wrap");
        this.add(labelFour);
        this.getContentPane().add(panel4);
        this.pack();
        this.setVisible(true);
    }

    public static void main(String[] args) {
        MainWindow window = new MainWindow();
        window.setLocationRelativeTo(null);
        window.runThreads();
    }

    public void runThreads() {
        Thread panelThread1 = new Thread(panel1);
        Thread panelThread2 = new Thread(panel2);
        Thread panelThread3 = new Thread(panel3);
        Thread panelThread4 = new Thread(panel4);

        panelThread1.start();
        panelThread2.start();
        panelThread3.start();
        panelThread4.start();
    }

}

Answer 1

The problem is:

Swing components should be created and manipulated on Event Dispatch Thread via SwingUtilities.invokeXXX block.

You dont do this. Have a read on:

• Concurrency in Swing

Answer 2

Your String counterAsString does not get updated every time the int counter gets

while(counter < 100) {
            // put this here
            >>  counterAsString = Integer.toString(counter);
            textFieldOne.setText(counterAsString);
            textFieldTwo.setText(counterAsString);
            System.out.println("Counter 1 = " + counterAsString + ", Counter 2 = " + counterAsString);
            counter++;
}