Question

我的JPanel出了问题。我用界面构建了一个html / css scraper。该接口有一个JTextArea，它使用刮刀完成的步骤进行更新，如＃34;找到HTML＆＃34;和＃34;保存的文件成功＆＃34;。我想在代码运行时将这些消息添加到JTextArea。一个简单的检查显示更新正在使用observerpattern，但所有消息都不会显示，直到所有代码完成。

来自可观察类的示例代码（触发100次）：

private void addItem(String line, char type, String classOrId) {
    String[] lineSplit = line.split(classOrId+"="+type);
    lineSplit = lineSplit[1].split(""+type);
    lineSplit = lineSplit[0].split(" ");
    for (String a : lineSplit) {
        if(classOrId == "id"){
            if (!usedIds.contains(a)) {
                usedIds.add(a);
            }
        }
        else if(classOrId == "class"){
            if (!usedClasses.contains(a)) {
                usedClasses.add(a);
            }
        }
        consoleText = consoleText + "Class \"" + a + "\" is found.";  
        setChanged();
        notifyObservers();
    }
}

来自观察者类的示例代码：

public class ScraperView extends JPanel implements Observer {
    Scraper scraper;
    public ScraperView(Scraper scraper){
        this.scraper = scraper;
        scraper.addObserver(this);
        this.setLayout(new BoxLayout(this, BoxLayout.Y_AXIS));
        refresh();
    }

    private void refresh() { 
        System.out.println("TrIGGER");
        removeAll(); 
        int removedClasses = scraper.getRemovedClasses();
        int totalClasses = scraper.getTotalClasses();
        JLabel classesText = new JLabel("   Total Classes:       "+ Integer.toString(totalClasses));
        JLabel removedClassesText = new JLabel("   Removed Classes: "+ Integer.toString(removedClasses));
        this.add(classesText);
        this.add(removedClassesText);
        this.revalidate();
        this.repaint();
    }
    @Override
    public void update(Observable o, Object arg) {
        refresh();
    }
}

有没有办法等到jPanel更新？我注意到代码每次都被触发，但是没有更新..

Answer 1

您应该查看SwingWorker类，它旨在同时更新UI时在线程中执行任务。

Answer 2

您每次更新时都在创建和添加新的 JLabel ，这是一个坏主意，您应该创建一次标签，然后更新它们，您还应该确保在更新时更新它们您可以使用SwingUtilities.invokeLater(Runnable)

执行的UI线程

public class ScraperView extends JPanel implements Observer {
    Scraper scraper;
    JLabel classesText = new JLabel();
    JLabel removedClassesText = new JLabel();

    public ScraperView(Scraper scraper){
        this.scraper = scraper;
        scraper.addObserver(this);
        this.setLayout(new BoxLayout(this, BoxLayout.Y_AXIS));
        this.add(classesText);
        this.add(removedClassesText);
        refresh();
    }

    private void refresh() { 
        System.out.println("TrIGGER");
        int removedClasses = scraper.getRemovedClasses();
        int totalClasses = scraper.getTotalClasses();
        classesText.setText("   Total Classes:       "+ Integer.toString(totalClasses));
        removedClassesText.setText("   Removed Classes: "+ Integer.toString(removedClasses));
    }
    @Override
    public void update(Observable o, Object arg) {
        SwingUtilities.invokeLater(this::refresh);
    }
}

Java Jpanel仅在完成代码后更新

2 个答案: