java 在 JTextArea 中设置插入符号位置
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Setting caret position in JTextArea
提问by nicks
I have a JTextArea. I have a function that selects some amount of text when some combination is called. It's done properly. The thing is, I want to move caret to the selection beginning when some text is selected and VK_LEFT is pressed. KeyListener is implemented properly, I tested it in other way. The thing is, that when I write following code:
我有一个 JTextArea。我有一个函数，可以在调用某些组合时选择一定数量的文本。它做得很好。The thing is, I want to move caret to the selection beginning when some text is selected and VK_LEFT is pressed. KeyListener 实现正确，我以其他方式对其进行了测试。问题是，当我编写以下代码时：
@Override public void keyPressed( KeyEvent e) {
if(e.getKeyChar()==KeyEvent.VK_LEFT)
if(mainarea.getSelectedText()!=null)
mainarea.setCaretPosition(mainarea.getSelectionStart());
}
and add an instance of this listener to mainarea, select some text (using my function) and press left arrow key, the caret position is set to the end of selection... And I wont it to be in the beginning... What's the matter? :S
并将此侦听器的实例添加到 mainarea，选择一些文本（使用我的函数）并按向左箭头键，插入符号位置设置为选择的末尾...我不会在开头...什么什么事？:S
回答by kleopatra
Here's a code snippet
这是一个代码片段
Action moveToSelectionStart = new AbstractAction("moveCaret") {
@Override
public void actionPerformed(ActionEvent e) {
int selectionStart = textComponent.getSelectionStart();
int selectionEnd = textComponent.getSelectionEnd();
if (selectionStart != selectionEnd) {
textComponent.setCaretPosition(selectionEnd);
textComponent.moveCaretPosition(selectionStart);
}
}
public boolean isEnabled() {
return textComponent.getSelectedText() != null;
}
};
Object actionMapKey = "caret-to-start";
textComponent.getInputMap().put(KeyStroke.getKeyStroke("LEFT"), actionMapKey);
textComponent.getActionMap().put(actionMapKey, moveToSelectionStart);
Note: it's not recommended to re-define typically installed keybindings like f.i. any of the arrow keys, users might get really annoyed ;-) Better look for some that's not already bound.
注意：不建议重新定义通常安装的键绑定，例如任何箭头键，用户可能会非常恼火;-) 最好寻找一些尚未绑定的键。
