How to set focus on specific JTextfield inside JOptionPane when created?

坚强是说给别人听的谎言 提交于 2019-11-29 15:12:53

You could let the txt2 component request focus once it is added by overriding addNotify. Like this:

private JTextArea txt2 = new JTextArea() {
    public void addNotify() {
        super.addNotify();
        requestFocus();
    }
};

Here's a fully functional / tested version of your program:

import java.awt.Dimension;
import javax.swing.*;
public class Test extends JPanel {
    private JTextArea txt1 = new JTextArea();
    private JTextArea txt2 = new JTextArea() {
        public void addNotify() {
            super.addNotify();
            requestFocus();
        }
    };

    public Test() {
        setLayout(null);
        setPreferredSize(new Dimension(200, 100));
        txt1.setBounds(20, 20, 220, 20);
        txt2.setBounds(20, 45, 220, 20);
        txt1.setText("Text Field #1");
        txt2.setText("Text Field #2");
        add(txt1);
        add(txt2);
    }

    private void display() {
        Object[] options = { this };
        JOptionPane pane = new JOptionPane();
        pane.showOptionDialog(null, null, "Title", JOptionPane.DEFAULT_OPTION,
                JOptionPane.PLAIN_MESSAGE, null, options, txt2);
    }

    public static void main(String[] args) {
        new Test().display();
    }
}

I gave you the answer in your last question (http://stackoverflow.com/questions/6475320/how-to-set-the-orientation-of-jtextarea-from-right-to-left-inside-joptionpane). The concept is the same. Think about the solution given and understand how it works so you can apply it in different situations.

If you still don't understand the suggestion then see DialogFocus for reusable code.

Why not use a JDialog or JFrame for this purpose?

   public void display2() {
      JDialog dialog = new JDialog(null, "Title", ModalityType.APPLICATION_MODAL);
      dialog.getContentPane().add(this);
      dialog.pack();
      dialog.setLocationRelativeTo(null);
      txt2.requestFocusInWindow();
      dialog.setVisible(true);
   }

You could use a workaround proposed in JDK-5018574 bug report.

Instead of

txt2.requestFocus();

use

txt2.addHierarchyListener(e -> {
    if(e.getComponent().isShowing() && (e.getChangeFlags() & HierarchyEvent.SHOWING_CHANGED) != 0)
        SwingUtilities.invokeLater(e.getComponent()::requestFocusInWindow);
});

I modified the solution to use Java 8 features. For older versions of Java, see the original workaround.

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