How do I make the caret of a JTextComponent skip selected text?

问题

the normal behaviour of native text fields in many environments is as follows:

Textfield with text "abcdefg". I use the mouse to select "efg" from left to right. The caret is now behind "g". When I move the caret to the left by pressing the cursor left key once, the selection is removed and the caret is right before "e". When I do the same in a JTextField or JTextArea (tested on Mac OS) doing the exact same thing results in the caret being right before "g".

I know how I could change that programmatically by using a KeyListener and registering it with each component but I am looking for a way to change that for my entire application. Is that possible? Is there a Flag, I am not finding or do I have to hack my look and feel?

Thanks

回答1:

I am looking for a way to change that for my entire application

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.*;

public class CaretAction extends TextAction
{
    private boolean caretForward;

    public CaretAction(boolean caretForward)
    {
        super(caretForward ? "Caret Forward" : "Caret Backward");
        this.caretForward = caretForward;
    }

    public void actionPerformed(ActionEvent e)
    {
        JTextComponent textComponent = getFocusedComponent();

        int start = textComponent.getSelectionStart();
        int end = textComponent.getSelectionEnd();
        int offset = textComponent.getCaretPosition();

        if (start != end)
        {
            if (caretForward)
                offset = (offset == end) ? offset + 1 : end;
            else
                offset = (offset == start) ? offset -1 : start;
        }
        else
        {
            offset += (caretForward) ? 1 : -1;
        }

        offset = Math.max(offset, 0);
        offset = Math.min(offset, textComponent.getDocument().getLength());
        textComponent.setCaretPosition( offset );
    }

    private static void createAndShowUI()
    {
        JTextField textField1 = new JTextField(10);
        JTextField textField2 = new JTextField(10);

        JPanel panel = new JPanel();
        panel.add( textField1 );
        panel.add( textField2 );

        JFrame frame = new JFrame("SSCCE");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add( panel );
        frame.pack();
        frame.setLocationByPlatform( true );
        frame.setVisible( true );

        ActionMap map = (ActionMap)UIManager.get("TextField.actionMap");
        map.put(DefaultEditorKit.backwardAction, new CaretAction(false));
        map.put(DefaultEditorKit.forwardAction, new CaretAction(true));
    }

    public static void main(String[] args)
    {
        EventQueue.invokeLater(new Runnable()
        {
            public void run()
            {
                createAndShowUI();
            }
        });
    }
}

You would also need to change the ActionMap for JTextArea, JFormattedTextField ...

回答2:

What you can do is addCaretListener :

     anyField.addCaretListener(new CaretListener() {
        public void caretUpdate(CaretEvent evt) {
            anyFieldCaretUpdate(evt);
        }
       });

And set the Caret at the last again:

  private void anyFieldCaretUpdate(CaretEvent evt) {

     anyField.setCaretPosition(anyField.getText().length());
        }

来源：https://stackoverflow.com/questions/15554728/how-do-i-make-the-caret-of-a-jtextcomponent-skip-selected-text

标签

java

swing

selection

caret

jtextcomponent