Jtextfield和keylistener [英] Jtextfield and keylistener
本文介绍了Jtextfield和keylistener的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我想要一个jtextfield(jt)我想要用户输入e
,例如单词示例
将自动写入jtextfield。
I have a jtextfield (jt) where I want as soon as the user types "e"
for example in it, the word "Example"
to be written automatically in the jtextfield.
我使用代码:
KeyListener keyListener = new KeyListener() {
public void keyPressed(KeyEvent e) {
jt.setText("Example");
}
}
但这会给出示例按下e时
!有任何想法吗?非常感谢
But this gives "Examplee"
when e is pressed! Any ideas? Thanks a lot
推荐答案
不要在文本组件上使用 KeyListener
,有一系列问题(未通知,变异异常,当用户将某些内容粘贴到字段中时未通知),而是应该使用 DocumentFilter
Don't use KeyListener
on text components, there are a rafter of issues (not been notified, mutation exceptions, not been notified when the user pastes something into the field), instead, you should be using a DocumentFilter
例如......
import java.awt.EventQueue;
import java.awt.GridBagLayout;
import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.text.AbstractDocument;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.DocumentFilter;
public class TextFieldExample {
public static void main(String[] args) {
new TextFieldExample();
}
public TextFieldExample() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JTextField field = new JTextField(20);
((AbstractDocument)field.getDocument()).setDocumentFilter(new ExampleExpandingDocumentFilter());
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new GridBagLayout());
frame.add(field);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class ExampleExpandingDocumentFilter extends DocumentFilter {
@Override
public void insertString(FilterBypass fb, int offset, String text, AttributeSet attr) throws BadLocationException {
System.out.println("I" + text);
super.insertString(fb, offset, text, attr);
}
@Override
public void replace(FilterBypass fb, int offset, int length, String text, AttributeSet attrs) throws BadLocationException {
if ("e".equalsIgnoreCase(text)) {
text = "example";
}
super.replace(fb, offset, length, text, attrs);
}
}
}
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