Java JComboBox实例

本文概述

• JComboBox类声明
• Java JComboBox示例
• 带有ActionListener的Java JComboBox示例

Choice类的对象用于显示选择的弹出菜单。用户选择的选项显示在菜单顶部。它继承了JComponent类。

JComboBox类声明

我们来看一下javax.swing.JComboBox类的声明。

public class JComboBox extends JComponent implements ItemSelectable, ListDataListener, ActionListener, Accessible

常用的构造函数：

常用方法：

Java JComboBox示例

import javax.swing.*;  
public class ComboBoxExample {  
JFrame f;  
ComboBoxExample(){  
    f=new JFrame("ComboBox Example");  
    String country[]={"India", "Aus", "U.S.A", "England", "Newzealand"};      
    JComboBox cb=new JComboBox(country);  
    cb.setBounds(50, 50, 90, 20);  
    f.add(cb);      
    f.setLayout(null);  
    f.setSize(400, 500);  
    f.setVisible(true);       
}  
public static void main(String[] args) {  
    new ComboBoxExample();       
}  
}

输出：

带有ActionListener的Java JComboBox示例

import javax.swing.*;  
import java.awt.event.*;  
public class ComboBoxExample {  
JFrame f;  
ComboBoxExample(){  
    f=new JFrame("ComboBox Example"); 
    final JLabel label = new JLabel();        
    label.setHorizontalAlignment(JLabel.CENTER);
    label.setSize(400, 100);
    JButton b=new JButton("Show");
    b.setBounds(200, 100, 75, 20);
    String languages[]={"C", "C++", "C#", "Java", "PHP"};      
    final JComboBox cb=new JComboBox(languages);  
    cb.setBounds(50, 100, 90, 20);  
    f.add(cb); f.add(label); f.add(b);  
    f.setLayout(null);  
    f.setSize(350, 350);  
    f.setVisible(true);     
    b.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {     
String data = "Programming language Selected: " 
   + cb.getItemAt(cb.getSelectedIndex());
label.setText(data);
}
}); 	    
}  
public static void main(String[] args) {  
    new ComboBoxExample();       
}  
}

输出：