listevt.java

java练习程序

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

public class ListEVT extends Applet implements ItemListener,ActionListener
{
	List list1,list2;
	TextArea text1,text2;
	public void init()
	{
		setLayout (new GridLayout(2,2));
		list1=new List(3,false);
		list2=new List(3,false);
		Panel p1=new Panel();p1.add(list1);
		Panel p2=new Panel();p1.add(list2);
		text1=new TextArea(10,10);
		text2=new TextArea(10,10);
		
		list1.add("1+2+3+...");
		list1.add("1*1+2*2+3*3+...");
		list1.add("1*1*1+2*2*2+3*3*3+...");
		for(int i=1;i<101;i++)
		{
			list2.add("前"+i+"项计算结果");
		}
		add(p1);
		add(p2);
		add(text1);
		add(text2);
		list1.addItemListener(this);
		list2.addActionListener(this);
        }
        public void itemStateChanged(ItemEvent e)
        {
        	if(e.getItemSelectable()==list1)
        	{
        		if(list1.getSelectedIndex()==0)
        		{
        			text1.setText("计算1+2+3+...");
        		}
        		else if(list1.getSelectedIndex()==1)
        		{
        			text1.setText("计算1*1+2*2+3*3+...");
        		}
        		else if(list1.getSelectedIndex()==2)
        		{
        			text1.setText("计算1*1*1+2*2*2+3*3*3+...");
        		}
        	}
        }

        public void actionPerformed(ActionEvent e)
        {
        	if(e.getSource()==list2)
        	{
        		if(list1.getSelectedIndex()==0)
        		{
        			String s=list2.getSelectedItem();
        			int n=list2.getSelectedIndex();
        			long sum=0;
        			for(long i=1;i<n+2;i++)
        			{
        				sum=sum+i;
        			}
        			text2.setText("结果:"+sum+" list2: "+n);
        		}
        		else if(list1.getSelectedIndex()==1)
        		{
        			String s=list2.getSelectedItem();
        			int n=list2.getSelectedIndex();
        			long sum=0;
        			for(long i=1;i<n+2;i++)
        			{
        				sum=sum+i*i;
        			}
        			text2.setText("结果:"+sum+" list2: "+n);
        		}
        		else if(list1.getSelectedIndex()==2)
        		{
        			String s=list2.getSelectedItem();
        			int n=list2.getSelectedIndex();
        			long sum=0;
        			for(long i=1;i<n+2;i++)
        			{
        				sum=sum+i*i*i;
        			}
        			text2.setText("结果:"+sum+" list2: "+n);
        		}
        	}
        }
}