Java.swing.ComboBox不能转换为Button classException
出于某种原因，我不知道为什么我的ComboBox不能按钮上的情况。 请帮忙：
码：
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
public class LocalBank implements ActionListener {
JFrame frame;
JPanel contentPane;
JLabel label1;
JLabel label2;
JLabel label3;
JTextField accNumber;
JTextField withdraw;
JTextField text3;
JButton avgButton;
JLabel average;
JComboBox plantNames;
JTextField firstname;
JTextField lastname;
JTextField beggining;
JButton submit;
JLabel accNumLabel;
JLabel withdawLabel;
JLabel firstnameLabel;
JLabel lastnameLabel;
JLabel begginingLabel;
public LocalBank() {
// TODO Auto-generated constructor stub
frame = new JFrame("Semiseter");
contentPane = new JPanel();
contentPane.setLayout(new BoxLayout(contentPane,BoxLayout.PAGE_AXIS));
contentPane.setBorder(BorderFactory.createEmptyBorder
(20, 20, 20, 20));
label1 = new JLabel("Enter An Integer");
label1.setAlignmentX(JLabel.LEFT_ALIGNMENT);
contentPane.add(label1);
String[] names = {"Deposit", "Withdrawal", "Check Balance","Add Account","Remove Account"};
plantNames = new JComboBox(names);
plantNames.setAlignmentX(JComboBox.LEFT_ALIGNMENT);
plantNames.setSelectedIndex(0);
plantNames.addActionListener(this);
contentPane.add(plantNames);
accNumLabel = new JLabel("Account Number");
contentPane.add(accNumLabel);
accNumber = new JTextField();
contentPane.add(accNumber);
withdawLabel = new JLabel("Amount of deposit/withdrawal:");
contentPane.add(withdawLabel);
withdraw = new JTextField("");
contentPane.add(withdraw);
firstnameLabel = new JLabel("First Name:");
contentPane.add(firstnameLabel);
firstname = new JTextField();
contentPane.add(firstname);
lastnameLabel = new JLabel("Last Name:");
contentPane.add(lastnameLabel);
lastname = new JTextField("");
contentPane.add(lastname);
begginingLabel = new JLabel("Beginning Balance:");
contentPane.add(begginingLabel);
beggining = new JTextField("");
contentPane.add(beggining);
submit = new JButton("Process Transaction");
submit.addActionListener(this);
submit.setActionCommand("Submit");
contentPane.add(submit);
frame.setContentPane(contentPane);
/* Size and then display the frame. */
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setVisible(true);
}
private static void runGUI() {
JFrame.setDefaultLookAndFeelDecorated(true);
LocalBank greeting = new LocalBank();
}
public static void main(String[] args) {
/* Methods that create and show a GUI should be
run from an event-dispatching thread */
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
runGUI();
}
});
}
public void actionPerformed(ActionEvent event) {
// TODO Auto-generated method stub
JComboBox comboBox = (JComboBox)event.getSource();
String plantName = (String)comboBox.getSelectedItem();
String eventString = event.getActionCommand();
if (plantName == "Deposit") {
accNumLabel.setVisible(true);
accNumber.setVisible(true);
withdawLabel.setVisible(true);
withdraw.setVisible(true);
firstnameLabel.setVisible(false);
firstname.setVisible(false);
lastnameLabel.setVisible(false);
lastname.setVisible(false);
begginingLabel.setVisible(false);
beggining.setVisible(false);
if(eventString.equals("Submit")){
System.out.println("Person with account number " + accNumLabel.getText().toString() + " Withdraws $" + withdawLabel.getText().toString());
}
}
else if (plantName == "Withdrawal") {
accNumLabel.setVisible(true);
accNumber.setVisible(true);
withdawLabel.setVisible(true);
withdraw.setVisible(true);
firstnameLabel.setVisible(false);
firstname.setVisible(false);
lastnameLabel.setVisible(false);
lastname.setVisible(false);
begginingLabel.setVisible(false);
beggining.setVisible(false);
}
else if (plantName == "Check Balance") {
accNumLabel.setVisible(true);
accNumber.setVisible(true);
firstnameLabel.setVisible(false);
firstname.setVisible(false);
lastnameLabel.setVisible(false);
lastname.setVisible(false);
begginingLabel.setVisible(false);
beggining.setVisible(false);
withdawLabel.setVisible(false);
withdraw.setVisible(false);
}
else if (plantName == "Add Account") {
accNumLabel.setVisible(false);
accNumber.setVisible(false);
withdawLabel.setVisible(false);
withdraw.setVisible(false);
firstnameLabel.setVisible(true);
firstname.setVisible(true);
lastnameLabel.setVisible(true);
lastname.setVisible(true);
begginingLabel.setVisible(true);
beggining.setVisible(true);
}
else if (plantName == "Remove Account") {
accNumLabel.setVisible(true);
accNumber.setVisible(true);
withdawLabel.setVisible(false);
withdraw.setVisible(false);
firstnameLabel.setVisible(false);
firstname.setVisible(false);
lastnameLabel.setVisible(false);
lastname.setVisible(false);
begginingLabel.setVisible(false);
beggining.setVisible(false);
}
else{
accNumLabel.setVisible(false);
accNumber.setVisible(false);
withdawLabel.setVisible(false);
withdraw.setVisible(false);
firstnameLabel.setVisible(false);
firstname.setVisible(false);
lastnameLabel.setVisible(false);
lastname.setVisible(false);
begginingLabel.setVisible(false);
beggining.setVisible(false);
}
}
}
错误：
例外在线程 “AWT-EventQueue的-0” java.lang.ClassCastException：javax.swing.JButton中不能在javax.swing.AbstractButton.fireActionPerformed被转换为在javax.swing.JComboBox中LocalBank.actionPerformed（LocalBank.java:124）（来源不明）在javax.swing.AbstractButton中$ Handler.actionPerformed（来源不明）在javax.swing.DefaultButtonModel.fireActionPerformed（来源不明）在javax.swing.DefaultButtonModel.setPressed（来源不明）在javax.swing.plaf.basic中。在java.awt.Container的java.awt.Component.processEvent（Unknown Source）上的javax.swing.JComponent.processMouseEvent（Unknown Source）上的java.awt.Component.processMouseEvent（Unknown Source）上的BasicButtonListener.mouseReleased（Unknown Source）。的processEvent（未知来源）在java.awt.Component.dispatchEventImpl（未知来源）在java.awt.Container.dispatchEventImpl（未知来源）在java.awt.Component.dispatchEvent（未知来源）在java.awt.LightweightDispatcher.retargetMouseEvent（未知源）在java.awt.LightweightDispa tcher.processMouseEvent（未知来源）在java.awt.LightweightDispatcher.dispatchEvent（未知来源）在java.awt.Container.dispatchEventImpl（未知来源）在java.awt.Window.dispatchEventImpl（未知来源）在java.awt.Component中。 java.awt.EventQueue上的java.awt.EventQueue.dispatchEventImpl（Unknown Source）上的dispatchEvent（Unknown Source）java.awt.EventQueue上的$ 400（Unknown Source）java.awt.EventQueue上的$ 3.run（Unknown Source） .RUN（来源不明）在java.security.AccessController.doPrivileged（本机方法）在java.security.ProtectionDomain $ 1.doIntersectionPrivilege（来源不明）在java.security.ProtectionDomain $ 1.doIntersectionPrivilege（来源不明）在java.awt.EventQueue中java.awt.EventQueue上的$ 4.run（Unknown Source）在java.security.ProtectionDomain上的java.security.AccessController.doPrivileged（Native Method）处获得$ 4.run（Unknown Source）。java.awt处的$ 1.doIntersectionPrivilege（Unknown Source）。 EventQueue.dispatchEvent（Unknown Source）at java.awt.EventDispatchThread.pumpOneEven tForFilters（未知来源）在java.awt.EventDispatchThread.pumpEventsForFilter（未知来源）在java.awt.EventDispatchThread.pumpEventsForHierarchy（未知来源）在java.awt.EventDispatchThread.pumpEvents（未知来源）在java.awt.EventDispatchThread.pumpEvents（未知源）在java.awt.EventDispatchThread.run（未知源）
您已将ActionListseners添加到两个组件：Button和JComboBox。
所以，
event.getSource()指向Button，它不是ComboBox 我建议你添加一个ItemListener到你的组合框，而不是一个Action Listener（参见这个和关于ItemListener的链接）
链接地址: http://www.djcxy.com/p/73441.html上一篇: Java.swing.ComboBox cant be cast on Button classException