我有一个包含JPanel的Java JFrame。在JPanel中，有两个独立的JPanel。当用户单击第一个JPanel中的按钮时，需要将消息发送到另一个JPanel，通知它单击了哪个按钮。在像这样的对象之间发送消息的最简单方法是什么？
答案 0 :(得分：11)
对于mKorbel（和原始海报）：
我推荐的是更松散的耦合，一个JPanel不知道其他JPanel，并且所有连接都是通过某种控制来完成的。例如，借用一些代码：
CopyTextNorthPanel2.java
import java.awt.*;
import javax.swing.*;
public class CopyTextNorthPanel2 extends JPanel {
private static final long serialVersionUID = 1L;
public JTextField northField;
public CopyTextNorthPanel2() {
northField = new JTextField("Welcome World");
northField.setFont(new Font("Serif", Font.BOLD, 20));
northField.setPreferredSize(new Dimension(300, 25));
add(northField);
}
public String getNorthFieldText() {
return northField.getText();
}
}
CopyTextSouthPanel2.java
import java.awt.event.*;
import javax.swing.*;
public class CopyTextSouthPanel2 extends JPanel {
private static final long serialVersionUID = 1L;
private JTextField firstText = new JTextField("Desired TextField");
private JButton copyButton = new JButton("Copy text from JTextFields");
private CopyTextControl2 control;
public CopyTextSouthPanel2() {
copyButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if (control != null) {
control.copyAction();
}
}
});
add(firstText);
add(copyButton);
}
public void setControl(CopyTextControl2 control) {
this.control = control;
}
public void setFirstText(String text) {
firstText.setText(text);
}
}
CopyTextControl2.java
public class CopyTextControl2 {
private CopyTextNorthPanel2 northPanel;
private CopyTextSouthPanel2 southPanel;
public void copyAction() {
if (northPanel != null && southPanel != null) {
southPanel.setFirstText(northPanel.getNorthFieldText());
}
}
public void setNorthPanel(CopyTextNorthPanel2 northPanel) {
this.northPanel = northPanel;
}
public void setSouthPanel(CopyTextSouthPanel2 southPanel) {
this.southPanel = southPanel;
}
}
CopyText2.java
import java.awt.*;
import javax.swing.*;
public class CopyText2 {
private static void createAndShowUI() {
CopyTextNorthPanel2 northPanel = new CopyTextNorthPanel2();
CopyTextSouthPanel2 southPanel = new CopyTextSouthPanel2();
CopyTextControl2 control = new CopyTextControl2();
southPanel.setControl(control);
control.setNorthPanel(northPanel);
control.setSouthPanel(southPanel);
JPanel mainPanel = new JPanel(new BorderLayout());
mainPanel.add(northPanel, BorderLayout.NORTH);
mainPanel.add(Box.createRigidArea(new Dimension(100, 100)), BorderLayout.CENTER);
mainPanel.add(southPanel, BorderLayout.SOUTH);
JFrame frame = new JFrame("Copy Text");
frame.getContentPane().add(mainPanel);
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() {
public void run() {
createAndShowUI();
}
});
}
}
答案 1 :(得分：6)
您可以创建自定义事件，并为其附加一个或多个侦听器。
实现的正确方法是让Button ActionListener触发事件，然后让你的两个面板成为该事件的监听器。
答案 2 :(得分：3)
位于班级的顶层
public MyClass implements ActionListener {
...
myButton.addActionListener(this);
...
public void actionPerformed(ActionEvent e) {
//for example if you have more than one events that you need to handle
if(e.getSource().equals(myButton) {
//update your do some work on you jpanels
}
}
答案 3 :(得分：2)
例如，通过在类之间使用构造函数或（用于调试问题）使用JComponent
getParent()中提取值
import java.awt.*;
import javax.swing.*;
public class CopyTextFrame extends JFrame {
private static final long serialVersionUID = 1L;
private CopyTextNorthPanel northPanel;
private CopyTextCenterPanel centerPanel;
private CopyTextSouthPanel southPanel;
public void makeUI() {
northPanel = new CopyTextNorthPanel();
centerPanel = new CopyTextCenterPanel();
southPanel = new CopyTextSouthPanel();
northPanel.setName("northPanel");
centerPanel.setName("centerPanel");
southPanel.setName("southPanel");
centerPanel = new CopyTextCenterPanel();
centerPanel.setPreferredSize(new Dimension(300, 40));
southPanel = new CopyTextSouthPanel();
southPanel.setSourceTextField(northPanel.desText);
northPanel.setBorder(BorderFactory.createLineBorder(Color.BLACK, 1));
centerPanel.setBorder(BorderFactory.createLineBorder(Color.BLACK, 1));
southPanel.setBorder(BorderFactory.createLineBorder(Color.BLACK, 1));
setLayout(new BorderLayout(5, 5));
setDefaultCloseOperation(EXIT_ON_CLOSE);
add(northPanel, BorderLayout.NORTH);
add(centerPanel, BorderLayout.CENTER);
add(southPanel, BorderLayout.SOUTH);
pack();
setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
new CopyTextFrame().makeUI();
}
});
}
}
+
import javax.swing.*;
public class CopyTextCenterPanel extends JPanel {
private static final long serialVersionUID = 1L;
public CopyTextCenterPanel() {
}
}
+
import java.awt.*;
import javax.swing.*;
public class CopyTextNorthPanel extends JPanel {
private static final long serialVersionUID = 1L;
public JTextField desText;
public CopyTextNorthPanel() {
desText = new JTextField("Welcome World");
desText.setFont(new Font("Serif", Font.BOLD, 20));
desText.setPreferredSize(new Dimension(300, 25));
desText.setBorder(BorderFactory.createLineBorder(Color.BLACK, 1));
desText.addComponentListener(null);
desText.setName("desText");
add(desText);
}
public JTextField getDesText() {
return desText;
}
}
+
import java.awt.*;
import java.awt.event.ActionEvent;
import javax.swing.*;
public class CopyTextSouthPanel extends JPanel {
private static final long serialVersionUID = 1L;
private JTextField firstText;
private JButton copyButton;
private JTextField sourceTextField;
private String lds = "";
public CopyTextSouthPanel() {
firstText = new JTextField("Desired TextField");
firstText.setMinimumSize(new Dimension(300, 25));
firstText.setPreferredSize(new Dimension(300, 25));
firstText.setMaximumSize(new Dimension(300, 25));
copyButton = new JButton("Copy text from JTextFields");
copyButton.setMinimumSize(new Dimension(200, 25));
copyButton.setPreferredSize(new Dimension(200, 25));
copyButton.setMaximumSize(new Dimension(200, 25));
copyButton.addActionListener(new java.awt.event.ActionListener() {
@Override
public void actionPerformed(java.awt.event.ActionEvent evt) {
copyButtonActionPerformed(evt);
}
private void copyButtonActionPerformed(ActionEvent evt) {
System.out.print("Button pressed" + "\n");
Component[] comp = CopyTextSouthPanel.this.getParent().getComponents();
int nO = comp.length;
for (int i = 0; i < comp.length; ++i) {
if (comp[i] instanceof JPanel) {
String name = ((JPanel) comp[i]).getName();
if (name.equals("northPanel")) {
JPanel panel = (JPanel) comp[i];
Component[] comp1 = panel.getComponents();
int nO1 = comp1.length;
for (int ii = 0; ii < comp1.length; ++ii) {
if (comp1[ii] instanceof JTextField) {
String name1 = ((JTextField) comp1[ii]).getName();
if (!(name1 == null)) {
if (name1.equals("desText")) {
JTextField text = (JTextField) comp1[ii];
String str = text.getText();
firstText.setText(str);
System.out.print("set value -> " + str + "\n");
break;
}
}
}
}
break;
}
}
}
lds = sourceTextField.getText();
if (lds != null || (!(lds.isEmpty()))) {
firstText.setText(" Msg -> " + lds);
}
}
});
add(firstText, BorderLayout.EAST);
add(copyButton, BorderLayout.WEST);
}
public void setSourceTextField(JTextField source) {
this.sourceTextField = source;
}
}