How to retain selected text in JTextField when focus lost?

问题

Now finishing my custom menu popup, but the problem is that if I select some text in JTextField and click mouse button to show popup menu, then focus is transferred to popup window, AND selected text before are no longer highlighted. When focus is back to JTextField - selected text become highlighted again. How to make the selected text stay highlighted on focus lost?

回答1:

then focus is transferred to popup window, AND selected text before are no longer highlighted. When focus is back to JTextField - selected text become highlighted again. How to make the selected text stay highlighted on focus lost?

• you can to override DefaultCaret for JTextComponents

• you can to override Highlighter for JTextComponents

code example from DefaultCaret

class HighlightCaret extends DefaultCaret {

    private static final Highlighter.HighlightPainter unfocusedPainter = new DefaultHighlighter.DefaultHighlightPainter(Color.RED);
    private static final Highlighter.HighlightPainter focusedPainter = new DefaultHighlighter.DefaultHighlightPainter(Color.YELLOW);
    private static final long serialVersionUID = 1L;
    private boolean isFocused;

    @Override
    protected Highlighter.HighlightPainter getSelectionPainter() {
        return isFocused ? focusedPainter/*super.getSelectionPainter()*/ : unfocusedPainter;
    }

    @Override
    public void setSelectionVisible(boolean hasFocus) {
        if (hasFocus != isFocused) {
            isFocused = hasFocus;
            super.setSelectionVisible(false);
            super.setSelectionVisible(true);
        }
    }
}

with output

from code

import java.awt.*;
import javax.swing.*;
import javax.swing.text.DefaultCaret;
import javax.swing.text.DefaultHighlighter;
import javax.swing.text.Highlighter;

public class TestTextComponents {

    private static final long serialVersionUID = 1L;
    private JTextField jTextField1;
    private JTextField jTextField2;
    private JFrame frame = new JFrame("Default Caret");

    public TestTextComponents() {
        jTextField1 = new JTextField();
        jTextField2 = new JTextField();
        jTextField1.setText("jTextField1");
        jTextField2.setText("jTextField2");
        jTextField1.setCaret(new HighlightCaret());
        jTextField2.setCaret(new HighlightCaret());
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        frame.setResizable(false);
        frame.setLayout(new FlowLayout());
        frame.add(new JLabel("Please skip between text fields and watch persistent selection: "));
        frame.add(jTextField1);
        frame.add(jTextField2);
        frame.setTitle("Text component persistent selection");
        frame.pack();
        frame.setVisible(true);
    }

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

class HighlightCaret extends DefaultCaret {

    private static final Highlighter.HighlightPainter unfocusedPainter = new DefaultHighlighter.DefaultHighlightPainter(Color.RED);
    private static final Highlighter.HighlightPainter focusedPainter = new DefaultHighlighter.DefaultHighlightPainter(Color.YELLOW);
    private static final long serialVersionUID = 1L;
    private boolean isFocused;

    @Override
    protected Highlighter.HighlightPainter getSelectionPainter() {
        setBlinkRate(500); // otherwise is disabled, stopped
        return isFocused ? focusedPainter/*super.getSelectionPainter()*/ : unfocusedPainter;
    }

    @Override
    public void setSelectionVisible(boolean hasFocus) {
        if (hasFocus != isFocused) {
            isFocused = hasFocus;
            super.setSelectionVisible(false);
            super.setSelectionVisible(true);
        }
    }
}

EDIT have to restore Caret.setBlinkRate(500);

来源：https://stackoverflow.com/questions/18237317/how-to-retain-selected-text-in-jtextfield-when-focus-lost