GUI 添加了组件但显示时显示空白 [英] GUI added components but when displayed shows blank
问题描述
出于某种原因，当我在 main 中运行代码时它可以工作，但目前我只有在 JButton 时运行代码
For some reason, when I run the code in the main it works but currently I have the code only run when a JButton is
import java.awt.Color;
import java.util.Random;
import javax.swing.JFrame;
import javax.swing.JProgressBar;
public class JavaCompilingJOP {
private JFrame framed = new JFrame();
private JProgressBar bar = new JProgressBar(0,100); //0 through 100 is the compiling until reaches that number
private Color startProgress = Color.RED;
private int loadingPercent = 0;
public JavaCompilingJOP(){
framed.setLayout(null);
framed.setSize(500, 200);
framed.setTitle("Compiling JOptionPane...");
framed.setLocationRelativeTo(null);
//Ok now lets make the GUI happen boys!
framed.getContentPane().setBackground(Color.BLACK); //Because startProgress is ze theme of ze game!
bar.setForeground(startProgress);
bar.setStringPainted(true);
bar.setValue(loadingPercent);
bar.setString(loadingPercent + "%");
bar.setBounds(50, 50, 400, 100);
framed.add(bar);
System.out.println("Make visible an run!");
framed.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
framed.setResizable(false);
framed.setVisible(true);
doTimer();
}
private void doTimer(){
Random obj = new Random();
for(int i = 0; i < 100; i++){
loadingPercent++;
bar.setValue(loadingPercent); //Updates counter
bar.setString(loadingPercent + "%"); //Updates progressbar
startProgress = new Color(startProgress.getRed()-2,startProgress.getGreen()+2,startProgress.getBlue());
bar.setForeground(startProgress);
try{Thread.sleep(100 + obj.nextInt(200));}catch(Exception E){}
}
System.out.println("Java compiled!");
framed.setVisible(false);
}
}
出于某种原因，我在调用时得到的只是一个白色屏幕，它似乎忽略了关闭时的处理，因为当我点击关闭它时......它也没有.请记住，当我在 main 中运行它时，它可以工作，但是当在按钮的 ActionListener 中时，它给了我一个仍然执行进度条内容的空白屏幕.我坚持这一点.
For some reason all I am getting though when called is a white screen that seems to neglect disposing on close because when I hit to close it.. it doesn't either. Keep in mind that when I run it in the main it works but when inside the ActionListener of the button, it gives me a blank screen that still performs it's progressbar stuff. Im stuck on this.
推荐答案
您的 JButton 的 actionPerformed() 代码在 Java 事件调度线程 (EDT) 上执行，这这就是 GUI冻结"并且您看到黑屏的原因.
重要提示:
EDT 是一个特殊的线程，应该非常小心地处理.
请花点时间阅读 EDT 以及如何正确使用它此处.
Your JButton's actionPerformed() code gets executed on the Java event dispatch thread (EDT) and this is why the GUI "freezes" and you see a black screen.
Doing so, also blocks the "close" event from being executed as well as any other swing event.
Important:
The EDT is a special thread which should be handled very carefully.
Please take the time and read on EDT and how to properly use it here.
正确方法:
doTimer() 应该永远在 Java 事件调度线程 (EDT) 上运行，因为它模拟(我希望)一些长时间运行的任务.
为了确保我们正确处理 EDT，我们使用 SwingWorker.
SwingWorkers 是一种特殊结构，旨在在后台线程中执行冗长的 GUI 交互任务.
由于这是第一次处理有点棘手，我为您添加了以下代码:
Correct method:
doTimer() should never run on Java event dispatch thread (EDT) since it simulates (I hope) some long-running task.
To make sure we handle the EDT correctly we use a SwingWorker.
SwingWorkers are special constructs designed to perform lengthy GUI-interaction tasks in a background thread.
Since this is kinda tricky to handle for the first time, I added the following code for you:
@Override
public void actionPerformed(ActionEvent e) {
SwingWorker<Object, Object> sw = new SwingWorker<Object, Object>() {
@Override
protected Object doInBackground() throws Exception {
// Code here will be executed in a background thread
// This is where all background activities should happen.
doTimer();
return null;
}
};
sw.execute();
// doTimer(); Bad Idea as this will execute on EDT!
}
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