jcomboboxdemo.java

《Java语言程序设计》源代码 很好的JAVA入门的好的代码

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
class JComboBoxDemo extends JFrame implements ActionListener{
	private JTextField textField;
	private JComboBox comboBox;
	public JComboBoxDemo(){
		super("组合框范例");
		Container c=getContentPane();
		JPanel panel1=new JPanel();
		JPanel panel2=new JPanel();
		//创建组合框
		Label label1=new Label("城市列表：");
		String[] city={"北京","天津","上海","重庆","深圳"};
        comboBox=new JComboBox(city);
        comboBox.setEditable(true);//设置组合框为可编辑
        comboBox.addActionListener(this);
        panel1.add(label1);
		panel1.add(comboBox);
		c.add(panel1,BorderLayout.NORTH);
		//创建文本框
		Label label2=new Label("你选择的是：");
		textField=new JTextField(10);
        panel2.add(label2);
		panel2.add(textField);
	    c.add(panel2,BorderLayout.CENTER);
	}
	public void actionPerformed(ActionEvent e){
			Object citySelect=comboBox.getSelectedItem();//获取选中的条目
			String str=(String)citySelect;
			textField.setText(str);
	}
	public static void main(String args[]){
		JFrame frame=new JComboBoxDemo();
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.setSize(250,100);
		frame.setVisible(true);
 	}
}