Java：如何为 TextField 执行“onclick”？
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Java: How do I do a "onclick" for TextField?
提问by Strawberry
I want to make my text field clear the text when someone clicks it. How can I do this?
我想让我的文本字段在有人单击时清除文本。我怎样才能做到这一点？
回答by Buhake Sindi
on java.awt.TextFieldyou can add a MouseListenerlike so
在java.awt.TextField你可以添加一个MouseListener像这样
TextField field = new TextField();
field.addMouseListener(new MouseListener() {
public void mouseClicked(MouseEvent e) {
}
public void mousePressed(MouseEvent e) {
}
public void mouseReleased(MouseEvent e) {
}
public void mouseEntered(MouseEvent e) {
}
public void mouseExited(MouseEvent e) {
}
});
The reason being that java.awt.TextFieldis a subclass of java.awt.TextComponent(which, in turn, is a subclass of java.awt.Component). The Componentclass has a addMouseListener()method.
原因是它java.awt.TextField是 的子类java.awt.TextComponent（反过来又是 的子类java.awt.Component）。这个Component类有一个addMouseListener()方法。
Alternatively, you can replace MouseListenerwith java.awt.event.MouseAdapterhas it encapsulates all of MouseListener, MouseWheelListenerand MouseMotionListenermethods.
或者，您可以替换MouseListener为java.awt.event.MouseAdapterhas it 封装了所有MouseListener,MouseWheelListener和MouseMotionListener方法。
From JavaDoc (of MouseAdapter):
来自 JavaDoc（的MouseAdapter）：
An abstract adapter class for receiving mouse events. The methods in this class are empty. This class exists as convenience for creating listener objects.
Mouse events let you track when a mouse is pressed, released, clicked, moved, dragged, when it enters a component, when it exits and when a mouse wheel is moved.
用于接收鼠标事件的抽象适配器类。这个类中的方法是空的。此类的存在是为了方便创建侦听器对象。
鼠标事件让您可以跟踪鼠标何时按下、释放、单击、移动、拖动、何时进入组件、何时退出以及何时移动鼠标滚轮。
回答by Stan Kurilin
Probably, you need addMouseListener().
可能，你需要addMouseListener().
updIt would be smt like
upd就像 smt
TextField a = ...;
a.addMouseListener(new MouseAdapter(){
public void mouseReleased(MouseEvent e) {
//some stuff
}
});
upd2 fix keyListener to MouseListener
upd2 将 keyListener 修复为 MouseListener
回答by Mohamed Saligh
Try this:
试试这个：
TextField.setText("defaultText");
TextField.addMouseListener(new java.awt.event.MouseAdapter() {
public void mouseClicked(java.awt.event.MouseEvent evt) {
reSet(evt);
}
});
TextField.addFocusListener(new java.awt.event.FocusAdapter() {
public void focusGained(java.awt.event.FocusEvent evt) {
reSet(evt);
}
});
void reSet(java.awt.event.KeyEvent evt) {
String temp = jTextField1.getText();
TextField.setText(temp.equals("defaultText")? "" : temp);
}
