使用 Tab 键从 JTextArea 移动焦点

Posted 2023-02-26

【中文标题】使用 Tab 键从 JTextArea 移动焦点

【英文标题】：Moving focus from JTextArea using tab key

【发布时间】：2010-10-06 06:24:28

【问题描述】：

如前所述，我想更改 JTextArea 中的默认 TAB 行为（使其类似于 JTextField 或类似组件）

这是事件动作

private void diagInputKeyPressed(java.awt.event.KeyEvent evt) 
    if(evt.KEY_PRESSED == java.awt.event.KeyEvent.VK_TAB) 
        actionInput.transferFocus();
    

这是听者

diagInput.addKeyListener(new java.awt.event.KeyAdapter() 
    public void keyPressed(java.awt.event.KeyEvent evt) 
        diagInputKeyPressed(evt);
    
);

我也尝试了 evt.KEY_TYPED，但没有任何乐趣。

有什么想法吗？

快速编辑：我也试过用requestFocus() 代替transferFocus()

【问题讨论】：

非常类似于***.com/questions/5042429/…

【参考方案1】：

根据this class：

/**
 * Some components treat tabulator (TAB key) in their own way.
 * Sometimes the tabulator is supposed to simply transfer the focus
 * to the next focusable component.
 * <br/>
 * Here s how to use this class to override the "component's default"
 * behavior:
 * <pre>
 * JTextArea  area  = new JTextArea(..);
 * <b>TransferFocus.patch( area );</b>
 * </pre>
 * This should do the trick. 
 * This time the KeyStrokes are used.
 * More elegant solution than TabTransfersFocus().
 * 
 * @author kaimu
 * @since 2006-05-14
 * @version 1.0
 */
public class TransferFocus 

    /**
     * Patch the behaviour of a component. 
     * TAB transfers focus to the next focusable component,
     * SHIFT+TAB transfers focus to the previous focusable component.
     * 
     * @param c The component to be patched.
     */
    public static void patch(Component c) 
        Set<KeyStroke> 
        strokes = new HashSet<KeyStroke>(Arrays.asList(KeyStroke.getKeyStroke("pressed TAB")));
        c.setFocusTraversalKeys(KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, strokes);
        strokes = new HashSet<KeyStroke>(Arrays.asList(KeyStroke.getKeyStroke("shift pressed TAB")));
        c.setFocusTraversalKeys(KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, strokes);
    

注意patch() 可以更短，根据the comments 中的Joshua Goldberg，因为目标是恢复被JTextArea 覆盖的默认行为：

component.setFocusTraversalKeys(KeyboardFocusManager.FORWARD_TRAVERS‌​AL_KEYS, null);
component.setFocusTraversalKeys(KeyboardFocusManager.BACKWARD_TRAVERS‌​AL_KEYS, null);

这用于问题“How can I modify the behavior of the tab key in a JTextArea?”

---

previous implementation 确实涉及Listener，而transferFocus()：

   /**
     * Override the behaviour so that TAB key transfers the focus
     * to the next focusable component.
     */
    @Override
    public void keyPressed(KeyEvent e) 
        if(e.getKeyCode() == KeyEvent.VK_TAB) 
            System.out.println(e.getModifiers());
            if(e.getModifiers() > 0) a.transferFocusBackward();
            else a.transferFocus(); 
            e.consume();
        
    

e.consume(); 可能是您错过了使其适用于您的情况的原因。

【讨论】：

需要更改为 getKeyCode() 和 evt.consume() - evt.consume() 摆脱了制表符并使用 getKeyCode() 允许它使用制表符成功移动焦点。非常感谢:)

不客气。我想知道第一个实现（修改组件的 FocusTraversalKeys 的那个）在某种程度上不是“更干净”...

哇，答案很好，对细节的关注始终如一：)

patch 可以更简单，因为您想恢复被 JTextArea 覆盖的默认行为。仅 2 行：component.setFocusTraversalKeys(KeyboardFocusManager.FORWARD,BACKWARD_TRAVERSAL_KEYS, null) 见 ***.com/a/5043957/411282