Swing GUI 下的漫长过程:意外延迟 [英] Long process under Swing GUI : unexpected delay

问题描述

在这里解释我的问题是一个 MCVE，其中单击 JDialog 上的 JButton A 将打开 JDialog B:

To explain my question here is an MCVE where clicking clicking a JButton on JDialog A opens JDialog B:

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JDialog;

public class  DiagA extends JDialog  {

    private DiagB diag;

    public  DiagA() {

        super();
        setTitle("main diag");
        setSize(200, 150);
        setLocation(400,400);

        JButton btn = new JButton("Show DiagB");
        btn.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent arg0) {

                showDiag();
            }
        });
        add(btn, BorderLayout.NORTH);

        //make main frame visible
        setVisible(true);
    }

    void showDiag() {

        if(diag == null) {

            diag = new DiagB();

            //this prints out as expected
            System.out.println("set visible done");

            try {
                Thread.sleep(3000);
            } catch (InterruptedException ex) {}

            //only after the delay diag shows in full
        }
    }

    public static void main(String[] args) {
        new  DiagA();
    }
}

class DiagB extends JDialog  {

    public  DiagB() {

        super();
        setTitle("2nd diag");
        setSize(150, 100);
        setLocation(600,420);
        setLayout(new FlowLayout(FlowLayout.CENTER));
        getContentPane().setBackground(Color.YELLOW);
        setVisible(true);
    }
}

正如您在代码中看到的，我在创建 DiagB 后添加了 3 秒延迟.单击按钮 DiagB 显示如下:

As you can see in the code I added a 3 sec delay after creating DiagB. Clicking the button DiagBshows like this:

只有在 3 秒延迟结束后，DiagB才完整显示:

Only after the 3 sec delay ends, DiagBshows in full:

我的问题是:
一个.为什么DiagB在构造后没有完全显示?(仅当 showDiag() 返回时才完整显示).
b.我的问题的原因是 DiagB 需要通过 DiagA 中的长过程进行更新.
正确的更新方式是什么?是否需要为每个更新过程使用 SwingWorker ?

My questions are:
a. Why doesn't DiagBshow completely after it is constructed ? (It shows in full only when showDiag() returns).
b. The reason for my question is that DiagB needs to be updated, by long processes in DiagA.
What is the right way to update ? Does it require using a SwingWorker for every updating process ?

推荐答案

a.showDiag 在 GUI 线程上运行.当您使 GUI 线程休眠时，GUI 将完全死亡.

a. showDiag runs on the GUI thread. The GUI will be completely dead while you make the GUI thread sleep.

B.是的，将 SwingWorker 用于长时间运行的任务，并使用 SwingUtilities.invokeLater() 将 GUI 更新任务提交回 GUI 线程.或者，实现 SwingWorker#done()，这是一种在 SwingWorker 任务完成后在 GUI 线程上运行的便捷方法.

b. Yes, use a SwingWorker for long-running tasks and use SwingUtilities.invokeLater() to submit GUI-updating tasks back to the GUI thread. Alternatively, implement SwingWorker#done() which is a convenience method that runs on the GUI thread after the SwingWorker task completes.

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