JLabel setText不更新文本 [英] JLabel setText not updating text

问题描述

我正在尝试使用setText()方法更新JLabel，但无法重绘JLabel.我必须使用repaint()方法来做到这一点吗?

I am trying to update a JLabel by using the setText() method, but I can't redraw JLabel. Do I have to use the repaint() method to do that?

这是代码的一部分，我没有收到任何错误，但是它没有更新JLabel.

Here is the part of code, I do not get any errors, but it is not updating the JLabel.

public void actionPerformed(ActionEvent e) {
    fc = new JFileChooser();
    if(e.getSource() == addButton) {
         int returnVal = fc.showOpenDialog(Main.this);
         if (returnVal == JFileChooser.APPROVE_OPTION) {
                filesList = fc.getSelectedFiles();
                setFilesList(filesList);

                StringBuilder logString = new StringBuilder();
                logString.append("Files to Convert " + "\n");
                for(int i = 0; i < getFiles().length; i++) {
                    logString.append(filesList[i].getAbsolutePath());
                }
                //JLabel log = new JLabel(); created above.
                log.setText(logString.toString());
            } else {
                //log.append("Open command cancelled by user." + newline);
        }
        //log.setCaretPosition(log.getDocument().getLength());
    }
}

推荐答案

JLabel不需要重画调用.只需调用setText(...)即可更改标签的文本，仅此而已.

JLabel requires no repaint call. Simply calling setText(...) will change the label's text, and that is all that is required.

我想知道您的问题是否是并发问题，您是否正在Swing事件线程上执行长时间运行的过程，并且这是否在阻止标签更新其文本.

I wonder if your problem is a concurrency issue, that you are doing a long-running process on the Swing event thread and that this is preventing your label from updating its text.

如果是这样，那么考虑在诸如SwingWorker提供的后台线程中进行长时间运行的进程，然后在Swing线程上更新JLabel的文本，例如可以通过SwingWorker的发布/进程方法来完成.

If so, then consider doing your long-running process in a background thread such as that provided by a SwingWorker, and then updating your JLabel's text on the Swing thread, such as can be done via the SwingWorker's publish/process methods.

有关此内容的更多信息，请查看课程:Swing中的并发教程.

For more on this, please have a look at the Lesson: Concurrency in Swing tutorial.

也Mario De ...关于无法在JLabel上打印简单的换行符是正确的. 1 +.

Also Mario De... is correct about not being able to print simple new-lines on a JLabel. 1+ to his answer.

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