ch6_e6_24.java

《java语言与面向对象程序设计题解及实验指导》源代码

import java.applet.*;
import java.awt.*;
import java.awt.event.*;

import java.util.*;

public class ch6_e6_24 extends Applet implements ActionListener
{
    Label prompt = new Label("请输入欲插入的字符串：");
    TextField input = new TextField(5);

    Vector dataVector = new Vector();

    public void init()              
    {        
        add(prompt);
        add(input);

        dataVector.removeAllElements();

        input.setText("");
        input.addActionListener(this);
    }
    
    public void paint(Graphics g)         //打印
    {
        int i=0;
        for(Enumeration e = dataVector.elements(); e.hasMoreElements(); i++)
        {
            try
            {
                g.drawString((String)(e.nextElement()), 
                    10+80*i, 40);
            }
            catch(NullPointerException npe)
            {
                System.out.println(i);
            }
        }
    }
    
    public void actionPerformed(ActionEvent e)
    {
        if(e.getSource() == input)     //用户在input中输入并回车时
        {   //记录数据
            String s = input.getText();
            
            int low=0, high=dataVector.size()-1, mid;
            
            while(low <= high)
            {
                mid = (high + low)/2;
                if(((String)(dataVector.get(mid))).compareToIgnoreCase(s) == 0)
                {
                    dataVector.insertElementAt(new String(s),mid);
                    System.out.println(s + "," + mid);   
                    break;
                }
                else if(((String)(dataVector.get(mid))).compareToIgnoreCase(s) > 0)
                    high = mid-1;
                else
                    low = mid+1;
            }
            if(low>high)
            {
                dataVector.insertElementAt(new String(s),low);
                System.out.println(s + "," + low);
            }
            input.setText(" ");
            repaint();
        }
    }
        
}