listexample.java

《JAVA程序设计教程》这本书的所有源代码

//ListExample.java

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;

public class ListExample
{  
	public static void main(String[] args)
	{  
		ListFrame frame = new ListFrame();
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.show();
	}
}

class ListFrame extends JFrame
{
	public ListFrame()
	{
		setTitle("ListExample");
		setSize(WIDTH, HEIGHT);

		Container contentPane = getContentPane();
		
		//建立容纳文本区的面板
		JPanel textPanel = new JPanel();
		//新建文本区
		myTextArea = new JTextArea(checkedLabel, 5, 20);
		JScrollPane textScrollPane = new JScrollPane(myTextArea);
		textPanel.add(textScrollPane);

		contentPane.add(textPanel);

		//建立容纳列表的面板
		listPanel = new JPanel();

		//新建列表框
		String[] courses = {"Math", "English", "Physics", "Chemic", 
			"Biology", "Politics"};
		courseList = new JList(courses);
		//设置列表中想显示的行数
		courseList.setVisibleRowCount(4);
		//增加事件监听器
		courseList.addListSelectionListener(new courseListener());

		JScrollPane listScrollPane = new JScrollPane(courseList);
		listPanel.add(listScrollPane);

		contentPane.add(listPanel, BorderLayout.SOUTH);
	}

	//事件监听器
	private class courseListener 
		implements ListSelectionListener
	{
		public void valueChanged(ListSelectionEvent event)
		{
			Object[] selectedCourses = courseList.getSelectedValues();
			int[] selectedIndexCourses = courseList.getSelectedIndices();
			StringBuffer tempSeletedText = new StringBuffer(checkedLabel);
			for (int i = 0; i < selectedCourses.length; i++)
			{
				String str1 = new String(selectedIndexCourses[i] + ",   ");
				String str2 = (String)selectedCourses[i];

				tempSeletedText.append(str1);
				tempSeletedText.append(str2);
				tempSeletedText.append("\n");
			}
			myTextArea.setText(tempSeletedText.toString());
		}
	}

	public static final int WIDTH = 300;
	public static final int HEIGHT = 250;
	public static final String checkedLabel="You choosed: \nIndex,  Course\n";

	private JTextArea myTextArea;
	private JList courseList;
	private JPanel listPanel;
}