java - JSpinner:自动选择 onFocus

Question

我想在用户通过我的表单中的 JTextFields 和 JSpinners 切换时实现自动选择。为此，我正在使用这个监听器:

public class AutoSelect implements FocusListener {

    @Override
    public void focusGained(final FocusEvent e) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                if (e.getSource() instanceof JTextField) {
                    try {
                        JTextField t = (JTextField) e.getComponent();
                        t.selectAll();
                    } catch (ClassCastException ex) {
                        // 
                    }
                }else if (e.getSource() instanceof JSpinner){
                    JSpinner spinner = (JSpinner)e.getComponent();
                    JTextField tf = ((JSpinner.DefaultEditor)spinner.getEditor()).getTextField();  
                    tf.selectAll();
                }
            }
        });
    }

    @Override
    public void focusLost(FocusEvent e) {
        // 
    }
}

只是它对我的微调器不起作用。事件被触发，正确的行被执行，但什么也没有发生。我怀疑我没有正确使用 .getTextField() 。有人对此有可行的解决方案吗？

Answer 1

• tf.selectAll(); 应该被包装到 invokeLater 中，一切都包含Focus 是相当异步的(更多内容在 Oracle 教程 How to use Focus, FocusSubsystem)，

• 然后 invokeLater(并非在所有情况下都适用于所有 JComponents，但是默认情况下)对于 JTextComponents 将此事件移动到队列的末尾，非常适合我

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

public class ComboBoxTwo extends JFrame {

    private static final long serialVersionUID = 1L;
    private JTextField text = new JTextField(15);
    private JSpinner spinner = new JSpinner(new SpinnerNumberModel(0, 0, 15, 1));

    public ComboBoxTwo() {
        text.setText("Something selectable");
        text.addFocusListener(fcsListener);
        JFormattedTextField format = ((JSpinner.DefaultEditor) spinner.getEditor()).getTextField();
        // or JTextField tf = ((JSpinner.DefaultEditor) spinner.getEditor()).getTextField();
        format.addFocusListener(fcsListener);
        //or tf.addFocusListener(fcsListener); // depends of type for SpinnerXxxModel 
        add(text, BorderLayout.NORTH);
        add(spinner, BorderLayout.SOUTH);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame frame = new ComboBoxTwo();
                frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
                frame.pack();
                frame.setVisible(true);
            }
        });
    }
//
    private FocusListener fcsListener = new FocusListener() {
        @Override
        public void focusGained(FocusEvent e) {
            dumpInfo(e);
        }

        @Override
        public void focusLost(FocusEvent e) {
            dumpInfo(e);
        }

        private void dumpInfo(FocusEvent e) {
            System.out.println("Source  : " + name(e.getComponent()));
            System.out.println("Opposite : " + name(e.getOppositeComponent()));
            System.out.println("Temporary: " + e.isTemporary());
            final Component c = e.getComponent();//works for editable JComboBox too
            if (c instanceof JFormattedTextField) {
                SwingUtilities.invokeLater(new Runnable() {
                    @Override
                    public void run() {
                        ((JFormattedTextField) c).setText(((JFormattedTextField) c).getText());
                        ((JFormattedTextField) c).selectAll();
                    }
                });
            } else if (c instanceof JTextField) {
                SwingUtilities.invokeLater(new Runnable() {
                    @Override
                    public void run() {
                        ((JTextField) c).setText(((JTextField) c).getText());
                        ((JTextField) c).selectAll();
                    }
                });
            }
        }

        private String name(Component c) {
            return (c == null) ? null : c.getName();
        }
    };
}