通过PropertyChangeListener同步JTextFields值 [英] Synchronize JTextFields Values by PropertyChangeListener
本文介绍了通过PropertyChangeListener同步JTextFields值的处理方法，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
我想在TXTFLD1的值复制 jTextField - TXTFLD1 的值到另一个 jTextField -TXTFLD2 变化。
我选择 propertychangelistener ，因为我无法检测到TXTFLD1的值何时发生变化，因为它被一些我现在无法修改的外部代码所改变。 / p>
测试代码如下：
public class TxtFldSync扩展JFrame {
private JButton BTN1 = null;
private JTextField TXTFLD1 = null;
private JTextField TXTFLD2 = null;
public static void main（String [] args）{
TxtFldSync thisClass = new TxtFldSync（）;
thisClass.setDefaultCloseOperation（JFrame.EXIT_ON_CLOSE）;
thisClass.setVisible（true）;
}
public TxtFldSync（）{
super（）;
this.setSize（300,200）;
BTN1 =新JButton（）;
BTN1.setBounds（new Rectangle（178,38,67,17））;
TXTFLD1 = new JTextField（）;
TXTFLD1.setBounds（new Rectangle（32,42,83,20））;
TXTFLD2 = new JTextField（）;
TXTFLD2.setBounds（new Rectangle（30,78,83,20））;
//监听器
TXTFLD1.addPropertyChangeListener（value，new PropertyChangeListener（）{
@Override
public void propertyChange（PropertyChangeEvent arg0）{
TXTFLD2.setText（TXTFLD1.getText（）+由更改侦听器设置）;
//这不起作用的原因是什么？
}
}）;
BTN1.addActionListener（new ActionListener（）{
@Override
public void actionPerformed（ActionEvent arg0）{
TXTFLD1.setText（Action Performed）;
/ / i使用属性更改侦听器为TXTFLD2设置相同的值
}
}）;
this.setContentPane（new Container（））;
this.getContentPane（）。add（BTN1）;
this.getContentPane（）。add（TXTFLD1）;
this.getContentPane（）。add（TXTFLD2）;
}
}
为什么属性更改侦听器无效。
这个问题的其他替代解决方案是什么？
解决方案
例如，正如StanislavL +1所建议的那样使用 DocumentListener ：
import java.awt.GridLayout;
import javax.swing。*;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
公共类TextLabelMirror {
private JPanel mainPanel = new JPanel（）;
private JTextField field = new JTextField（20）;
private JTextField field1 = new JTextField（20）;
public TextLabelMirror（）{
field.getDocument（）。addDocumentListener（new DocumentListener（）{
@Override
public void changedUpdate（DocumentEvent e ）{
updateLabel（e）;
}
@Override
public void insertUpdate（DocumentEvent e）{
updateLabel（e）;
}
@Override
public void removeUpdate（DocumentEvent e）{
updateLabel（e）;
}
private void updateLabel（ DocumentEvent e）{
java.awt.EventQueue.invokeLater（new Runnable（）{
@Override
public void run（）{
field1.setText（field .getText（））;
}
}）;
}
}）;
mainPanel.setLayout（new GridLayout（1,0,10,0））;
mainPanel.add（field）;
mainPanel.add（field1）;
}
public JComponent getComponent（）{
return mainPanel;
}
private static void createAndShowUI（）{
JFrame frame = new JFrame（TextLabelMirror）;
frame.getContentPane（）。add（new TextLabelMirror（）。getComponent（））;
frame.setDefaultCloseOperation（JFrame.EXIT_ON_CLOSE）;
frame.pack（）;
frame.setLocationRelativeTo（null）;
frame.setVisible（true）;
}
public static void main（String [] args）{
java.awt.EventQueue.invokeLater（new Runnable（）{
@覆盖
public void run（）{
createAndShowUI（）;
}
}）;
}
}
I want to copy the value of a jTextField - TXTFLD1 to another jTextField -TXTFLD2 when the value at TXTFLD1 changes.
I choose propertychangelistener because i cannot detect when the value at TXTFLD1 is changed, Because it is changed by some external code which i cannot modify now.
The test code is as follows :
public class TxtFldSync extends JFrame {
private JButton BTN1 = null;
private JTextField TXTFLD1 = null;
private JTextField TXTFLD2 = null;
public static void main(String[] args) {
TxtFldSync thisClass = new TxtFldSync();
thisClass.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
thisClass.setVisible(true);
}
public TxtFldSync() {
super();
this.setSize(300, 200);
BTN1 = new JButton();
BTN1.setBounds(new Rectangle(178, 38, 67, 17));
TXTFLD1 = new JTextField();
TXTFLD1.setBounds(new Rectangle(32, 42, 83, 20));
TXTFLD2 = new JTextField();
TXTFLD2.setBounds(new Rectangle(30, 78, 83, 20));
//listeners
TXTFLD1.addPropertyChangeListener("value", new PropertyChangeListener() {
@Override
public void propertyChange(PropertyChangeEvent arg0) {
TXTFLD2.setText(TXTFLD1.getText()+"set by change listener");
//this doesnot work why ?
}
});
BTN1.addActionListener( new ActionListener() {
@Override
public void actionPerformed(ActionEvent arg0) {
TXTFLD1.setText("Action Performed");
//i what to set same value to TXTFLD2 using property change listener
}
});
this.setContentPane(new Container());
this.getContentPane().add(BTN1);
this.getContentPane().add(TXTFLD1);
this.getContentPane().add(TXTFLD2);
}
}
Why the property change listener is not working. What are the other alternatives solution for this problem?
解决方案
For example, as StanislavL +1 suggested by using DocumentListener:
import java.awt.GridLayout;
import javax.swing.*;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
public class TextLabelMirror {
private JPanel mainPanel = new JPanel();
private JTextField field = new JTextField(20);
private JTextField field1 = new JTextField(20);
public TextLabelMirror() {
field.getDocument().addDocumentListener(new DocumentListener() {
@Override
public void changedUpdate(DocumentEvent e) {
updateLabel(e);
}
@Override
public void insertUpdate(DocumentEvent e) {
updateLabel(e);
}
@Override
public void removeUpdate(DocumentEvent e) {
updateLabel(e);
}
private void updateLabel(DocumentEvent e) {
java.awt.EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
field1.setText(field.getText());
}
});
}
});
mainPanel.setLayout(new GridLayout(1, 0, 10, 0));
mainPanel.add(field);
mainPanel.add(field1);
}
public JComponent getComponent() {
return mainPanel;
}
private static void createAndShowUI() {
JFrame frame = new JFrame("TextLabelMirror");
frame.getContentPane().add(new TextLabelMirror().getComponent());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
java.awt.EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
createAndShowUI();
}
});
}
}
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