当文本区域不可编辑时，按下键如何显示仅在jpanel中显示的消息文件？

Question

When i open file in jtextarea. I set to textarea to non editable by using textArea.setEditable(false) but in the when i press the key how to show the message in jpanel file is read only.

Thank you.

Answer 1

Don't use setEditable(false), use TextFilter instead:

import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.WindowConstants;
import javax.swing.text.AbstractDocument;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.DocumentFilter;
public class TextAreaTest {

    /**
     *
     * @param args
     */
    public static void main(String[] args) {

        final JFrame frm = new JFrame("Text field test");
        final JTextArea area = new JTextArea("Some text here", 20, 50);
        ((AbstractDocument) area.getDocument()).setDocumentFilter(new DocumentFilter() {
            /**
             * {@inheritDoc}
             */
            @Override
            public void remove(FilterBypass fb, int offset, int length) throws BadLocationException {
                JOptionPane.showMessageDialog(frm, "Area read only");
            }

            /**
             * {@inheritDoc}
             */
            @Override
            public void insertString(FilterBypass fb, int offset, String string, AttributeSet attr) throws BadLocationException {
                JOptionPane.showMessageDialog(frm, "Area read only");
            }

            /**
             * {@inheritDoc}
             */
            @Override
            public void replace(FilterBypass fb, int offset, int length, String text, AttributeSet attrs) throws BadLocationException {
                JOptionPane.showMessageDialog(frm, "Area read only");
            }
        });
        frm.add(new JScrollPane(area));
        frm.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        frm.pack();
        frm.setVisible(true);
    }
}

Answer 2

You can add a KeyListener to the text area, and in the keyPressed() method do what you want, eg show a dialog.

JTextArea ta = new JTextArea();
ta.addKeyListener(new KeyAdapter() {
    @Override
    public void keyPressed(KeyEvent e) {
        System.out.println("Key pressed, warn the user that this is read only!");
    }
});