Java线程：让EDT函数等待EDT关闭长时间运行的函数

Question

Suppose I have a function refresh() which calls two other functions, one is a long running clearData() function which needs to be run off the EDT and the other is a quick function repaint() which is run in the EDT and which repaints the GUI components.

refresh()
{
   clearData(); //off the EDT function
   repaint(); //in the EDT function
}

what is a proper way to deal with the repaint when a longer operation like clearData() need to be run. Is it letting the clearData thread run repaint() once it is finished a proper way? how can this be done?

Answer 1

Yes, run the repaint() after the clearData() is complete. You can use SwingUtilties.invokeLater() or similar to get the repaint() to run on the EDT.

Possible implementation

final Runnable CLEAR_THEN_REPAINT = new Runnable() {
    public void run() { 
        clearData(); 
        SwingUtilities.invokeLater(new Runnable() {
            public void run() { repaint(); }
        });
    }
};

void refresh() {
    if (SwingUtilities.isEventDispatchThread()) {
        new Thread(CLEAR_THEN_REPAINT).start();
    } else {
        CLEAR_THEN_REPAINT.run();
    }
}

Answer 2

refresh() {
    new Runnable(){
        clearData();
        SwingUtilities.invokeLater(new Runnable() {
            repaint();
        });
    }.run();
}

Notice that repaint will be registered to be invoked after clearData(); has returned, so, it's guaranteed that repaint() will execute after clearData() .