java TextField 不动态更新
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TextField not updating dynamically
提问by user2497398
this is a really simple code in which text on a button is copied to a TextField. The code works fine but the TextField is not updating instantly on clicking the button. It updates only after i click on the TextField or when i drag the form not on pressing the button instantly. why is this happening,this behavior is unexpected. i am testing this code on a nokia 501 emulator which supports LWUIT.
这是一个非常简单的代码，其中将按钮上的文本复制到 TextField。代码工作正常，但 TextField 不会在单击按钮时立即更新。它仅在我单击 TextField 或拖动表单而不是立即按下按钮时更新。为什么会发生这种情况，这种行为是出乎意料的。我正在支持 LWUIT 的诺基亚 501 模拟器上测试此代码。
a = new Form("CALCULATOR")
final TextArea data = new TextArea();
final Button ab = new Button("Some Value");
ab.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent arg0) {
// TODO Auto-generated method stub
data.setText(ab.getText());
}
});
a.addComponent(ab);
a.addComponent(data);
a.show();
}
回答by pundit
After setting the text in the textfield repaint it. This may work
在文本字段中设置文本后重新绘制它。这可能有效
data.setText(ab.getText());
data.validate(); or data.repaint();
回答by neb1
That happen because your Code. I explain:
那是因为你的代码。我解释：
you call to function actionPerformed: this is lisitner that call when user make action like "after i click on the TextField..".
您调用 actionPerformed 函数：这是当用户执行诸如“在我单击 TextField 之后..”之类的操作时调用的 lisitner。
what you need to do is simple:
你需要做的很简单：
a = new Form("CALCULATOR")
final TextArea data = new TextArea();
final Button ab = new Button("Some Value");
ab.addActionListener(new ActionListener(){
data.setText(ab.getText());
a.addComponent(ab);
a.addComponent(data);
a.show();
}
回答by smk pobon
a = new Form("CALCULATOR")
final TextArea data = new TextArea();
final Button ab = new Button("Some Value");
ab.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent arg0) {
// TODO Auto-generated method stub
// data.setText(ab.getText()); // You should not use this
// Use this instead
data.setText(ab.getActionCommand());
}
});
a.addComponent(ab);
a.addComponent(data);
a.show();
}
