如何从给定的代码中删除i / o异常

Question

import java.io.*;
import java.awt.*;
import java.awt.event.*;
import java.applet.Applet;
import java.awt.Graphics;
import java.awt.Color;


     public class MyGraphic5 extends java.applet.Applet implements ActionListener
     {

         boolean go =false;
            int x, oldx, y, oldy;
            double angle;

    Button drawButton =new Button("Draw");


         public void init()
        {
                add(drawButton);
                drawButton.addActionListener(this);
       }
     public void paint(Graphics screen)
       {
             resize(500,500);
             int x,y, oldx, oldy;
             double i=0;
             double a=0;
             double b=0;
             oldx=250;
             oldy=250;
             double ang=0;
             //oldx=(int)(a*Math.cos(i)+250);
             //oldy=(int)(b*Math.sin(i)+250);
             double angle;
             x=1;
           if (go==true)
           {
             for (i=0; i<800; i=i+1)
             {
                //screen.drawOval(175-i,80,i*2+10,10+i); //(x1,y1,width,height)
                a=a+.5;
                b=b+.5;
                ang=ang+.8;
                x=(int)(a*Math.cos(ang)+250);
                y=(int)(b*Math.sin(ang)+250);
                screen.drawLine(x,y, oldx, oldy);
                oldx=x;
                oldy=y;
                pause(1);
             }

           }
       }
       public void actionPerformed(ActionEvent event)
       {

                Object source = event.getSource();
                if (source.equals(drawButton))
                {
                    System.out.println("hi");
                    go=true;
                    repaint();
                }

          }

       void pause(int time)
        {
               try {
                   Thread.sleep(time);
               } catch (InterruptedException e) { }
           }

     }

Answer 1

该代码甚至不包含任何可能引发IOException的内容。

Answer 2

我按原样复制了你的代码，并且能够在没有I / O异常的appletviewer中编译和运行它...所以我不知道问题出在哪里......