JScrollPane scrollbar jumps down on JEditorPane.se

问题:

Every time (except first time) I set text in JEditorPane scrollbar jumps to the bottom of JEditorPane. Is there any way to avoid this? One way that I tried is to use setCaretPosition(0) after setText(). It works but it's not exactly what I need. Scrollbar jumps down and then jumps up. Is there a way to avoid any movement of scrollbar at settext()?

My code:

package test;

import javax.swing.JApplet;
import javax.swing.JButton;
import javax.swing.JEditorPane;
import javax.swing.JScrollPane;
import javax.swing.event.HyperlinkEvent;
import javax.swing.event.HyperlinkListener;

public class Test extends JApplet implements  HyperlinkListener {

    JEditorPane dataDisplayer = new JEditorPane();

    public void init() {
        ataDisplayer.setEditable(false);
        dataDisplayer.add(new JButton());
        dataDisplayer.setContentType("text/html");   
        JScrollPane jsp = new JScrollPane(dataDisplayer);
        dataDisplayer.setText("<a href=''>Change Text</a><br><br><br><br><br><br><br><br><br><br>bla");
        this.dataDisplayer.addHyperlinkListener(this);
        setContentPane(jsp);
    }

    @Override
    public void hyperlinkUpdate(HyperlinkEvent arg0) {
        dataDisplayer.setText("<a href=''>Change Text</a><br><br><br><br><br><br><br><br><br><br>bla bla");

    }

}

回答1:

There are different ways to go with that. One would be to simply avoid caret visibility adjustement, like this:

import java.awt.Rectangle;
import javax.swing.JButton;
import javax.swing.JEditorPane;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.SwingUtilities;
import javax.swing.event.HyperlinkEvent;
import javax.swing.event.HyperlinkListener;
import javax.swing.text.DefaultCaret;

public class TestEditorPane implements HyperlinkListener {

    private final class MyCaret extends DefaultCaret {

        @Override
        protected void adjustVisibility(Rectangle nloc) {

        }

    }

    JEditorPane dataDisplayer = new JEditorPane();
    private MyCaret caret;

    @Override
    public void hyperlinkUpdate(HyperlinkEvent arg0) {
        dataDisplayer.setText("<a href=''>Change Text</a><br><br><br><br><br><br><br><br><br><br>bla bla");

    }

    public void init() {
        JFrame frame = new JFrame();
        dataDisplayer.setEditable(false);
        caret = new MyCaret();
        dataDisplayer.setCaret(caret);
        dataDisplayer.add(new JButton());
        dataDisplayer.setContentType("text/html");
        JScrollPane jsp = new JScrollPane(dataDisplayer);
        dataDisplayer.setText("<a href=''>Change Text</a><br><br><br><br><br><br><br><br><br><br>bla");
        this.dataDisplayer.addHyperlinkListener(this);
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setContentPane(jsp);
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new TestEditorPane().init();
            }
        });
    }
}

回答2:

The following solved the problem for me, after 50 minutes of despair:

JEditorPane.grabFocus();
JEditorPane.setCaretPosition(20);