JLabel 文本未显示，JFrame 等待时冻结

Question

我正在编写剪刀石头布 GUI 应用程序，在我的 JPanel 之一中，我有一个 JLabel。这个 JLabel 应该说一秒钟石头，然后一秒钟布，然后一秒钟剪刀。到目前为止，它只在最后显示了拍摄的 JLabel 文本。我似乎无法弄清楚为什么。有人可以帮忙吗？

代码：

import javax.swing.*;
import java.awt.*;

class RockPaperScissorsShoot {
    public JFrame shootFrame;
    JPanel shootPanel;
    JLabel shootLabel;
    int flagThing = 0;

    public RockPaperScissorsShoot(Window gameWindow) {
        shootFrame = new JFrame();
        shootFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        shootFrame.setSize(250, 150);

        shootPanel = new JPanel(new GridLayout(1, 1));
        shootFrame.add(shootPanel);

        shootLabel = new JLabel();
        shootPanel.add(shootLabel);

        shootFrame.setVisible(true);

        shootFrame.setTitle("Rock!"); // the title changes
        shootLabel.setText("Rock!"); // but the JLabel text does not

        waitForMilSecs(1000);

        shootFrame.setTitle("Paper!");
        shootLabel.setText("Paper!");

        waitForMilSecs(1000);

        shootFrame.setTitle("Scissors!");
        shootLabel.setText("Scissors!");

        waitForMilSecs(1000);

        shootFrame.setTitle("Shoot!");
        shootLabel.setText("Shoot!"); //Except here, right here, the text shows up
    }

    public static void waitForMilSecs(long ms) {
        long checkMS = System.currentTimeMillis() + ms;
        while (System.currentTimeMillis() <= checkMS) {
            System.out.println("Not yet!");
        }
        System.out.println("NOW!");
    }
}

编辑：我尝试添加 SwingWorker 来处理单独线程中的等待。我仍然得到一个冻结的 GUI。代码：

import java.awt.*;
import java.util.concurrent.ExecutionException;
import javax.swing.*;
//import javax.swing.event.ChangeEvent;
import javax.swing.SwingWorker.StateValue;

class RockPaperScissorsShoot {
    public JFrame shootFrame;
    JPanel shootPanel;
    JLabel shootLabel;
    int flagThing = 0;

    public RockPaperScissorsShoot(Window gameWindow) {
        shootFrame = new JFrame();
        shootFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        shootFrame.setSize(250, 150);

        shootPanel = new JPanel(new GridLayout(1, 1));
        shootFrame.add(shootPanel);

        shootLabel = new JLabel();
        shootPanel.add(shootLabel);

        shootFrame.setVisible(true);

        changeText(false, "Rock!", shootLabel, shootFrame, 1);
        changeText(true, "Paper!", shootLabel, shootFrame, 1);
        changeText(true, "Scissors", shootLabel, shootFrame, 1);
        changeText(true, "Shoot!", shootLabel, shootFrame, 1);
    }

    public static void changeText(boolean wait, String text, JLabel shootLabel, JFrame shootFrame, long secondsToWait) {
        while (wait) {
            wait = waiter(secondsToWait * 1000);
        }
        shootFrame.setTitle(text);
        shootLabel.setText(text);
    }

    private static boolean waiter(long ms) {
        boolean keepGoing = false;
        SwingWorker sw1 = new SwingWorker() {

            @Override
            protected Boolean doInBackground() throws Exception {
                Thread.sleep(ms);
                // String res = "Finished Execution";
                return true;
            }

            @Override
            protected void done() {
                try {
                    System.out.println(get().toString());
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } catch (ExecutionException e) {
                    // Auto-generated catch block
                    e.printStackTrace();
                }
            }
        };

        // executes the swingworker on worker thread
        sw1.execute();

        while (sw1.getState() != StateValue.DONE) {
            System.out.println("Not done (debug)");
        }
        System.out.println("Done!");
        return false;
    }

    public static void waitForMilSecs(long ms) {
        long checkMS = System.currentTimeMillis() + ms;
        while (System.currentTimeMillis() <= checkMS) {
            System.out.println("Not yet!");
        }
        System.out.println("NOW!");
    }

    public static void wait(int ms) {
        try {
            Thread.sleep(ms);
        } catch (InterruptedException e) {
            System.out.println("Error waiting, cannot wait lol");
        }
    }
}

任何人都可以向我解释为什么我的 GUI 仍然冻结吗？

Answer 1

使用 [Swing] Timer。
请尝试以下操作。

import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.Timer;

public class RockPaperScissorsShoot implements ActionListener {
    private JFrame shootFrame;
    private JPanel shootPanel;
    private JLabel shootLabel;
    private int flagThing = 0;
    private Timer timer;

    public RockPaperScissorsShoot() {
        shootFrame = new JFrame();
        shootFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        shootFrame.setSize(250, 150);
        shootPanel = new JPanel(new GridLayout(1, 1));
        shootFrame.add(shootPanel);
        shootLabel = new JLabel();
        shootPanel.add(shootLabel);
        shootFrame.setVisible(true);
        timer = new Timer(1000, this);
        timer.start();
    }

    public void actionPerformed(ActionEvent event) {
        String text;
        switch (flagThing) {
            case 0:
                text = "Rock!";
                break;
            case 1:
                text = "Paper!";
                break;
            case 2:
                text = "Scissors!";
                break;
            case 3:
                text = "Shoot!";
                break;
            default:
                text = null;
        }
        if (text != null) {
            shootFrame.setTitle(text);
            shootLabel.setText(text);
        }
        flagThing++;
        if (flagThing > 3) {
            timer.stop();
        }
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(() -> new RockPaperScissorsShoot());
    }
}

JLabel 文本未显示，JFrame 等待时冻结

JLabel Text not Showing, JFrame Freezing on Wait

java

swing

jpanel

jlabel