Dynamically Update Tooltip Currently Displayed

问题:

I'm trying to got a tooltip which displays the current progress of a task. So I want that the tooltip text change while the tooltip is displayed. But, when I call setToolTipText() the displayed text remains the same until I exit the mouse from the tooltip component and enter again. And call setToolTipText(null) before doesn't change anything.

回答1:

Indeed it does not update itself, even when resetting the tooltip to null between calls.

So far, the only trick I found was to simulate a mouse-move event and forward it on the TooltipManager. It makes him think that the mouse has moved and that the tooltip must be relocated. Not pretty, but quite efficient.

Have a look at this demo code which displays a progress in % from 0 to 100:

import java.awt.MouseInfo;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
import javax.swing.ToolTipManager;

public class TestTooltips {

    protected static void initUI() {
        JFrame frame = new JFrame("test");
        final JLabel label = new JLabel("Label text");
        frame.add(label);
        frame.pack();
        frame.setVisible(true);
        Timer t = new Timer(1000, new ActionListener() {

            int progress = 0;

            @Override
            public void actionPerformed(ActionEvent e) {
                if (progress > 100) {
                    progress = 0;
                }
                label.setToolTipText("Progress: " + progress + " %");
                Point locationOnScreen = MouseInfo.getPointerInfo().getLocation();
                Point locationOnComponent = new Point(locationOnScreen);
                SwingUtilities.convertPointFromScreen(locationOnComponent, label);
                if (label.contains(locationOnComponent)) {
                    ToolTipManager.sharedInstance().mouseMoved(
                            new MouseEvent(label, -1, System.currentTimeMillis(), 0, locationOnComponent.x, locationOnComponent.y,
                                    locationOnScreen.x, locationOnScreen.y, 0, false, 0));
                }
                progress++;
            }
        });
        t.start();
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                initUI();
            }
        });
    }
}

回答2:

Here's a simplified version of Guillaume Polet's answer which is self-contained in a single method. This code assumes one has called component.setToolTip("..."); previously. This code does not show how to periodically update the tooltip to show the progress.

public static void showToolTip(JComponent component)
{
   ToolTipManager manager;
   MouseEvent event;
   Point point;
   String message;
   JComponent component;
   long time;

   manager = ToolTipManager.sharedInstance();
   time    = System.currentTimeMillis() - manager.getInitialDelay() + 1;  // So that the tooltip will trigger immediately
   point   = component.getLocationOnScreen();
   event   = new MouseEvent(component, -1, time, 0, 0, 0, point.x, point.y, 1, false, 0);

   ToolTipManager.
      sharedInstance().
      mouseMoved(event);
}