报错 java.lang.StringIndexOutOfBoundsException

Question

package Test;import java.io.*;import java.awt.*;import java.awt.event.*;import javax.swing.*;public class ReadFileData { public static void main(String ags[]){  int b;  Label lab;  TextArea textArea;  byte temp[]=new byte[100];  Frame window=new Frame();window.setSize(400,400);  lab=new Label();  lab.setText("文件d:/write.txt的内容如下：");textArea=new TextArea(10,16);  window.add(lab,BorderLayout.NORTH);window.add(textArea,BorderLayout.CENTER);  window.validate();window.setVisible(true);  window.addWindowListener(new WindowAdapter()    {   public  void windowClosing(WindowEvent e){    System.exit(0);   }    });  try{   File f=new File("D:/迅雷下载/test.txt");   FileInputStream readfile=new FileInputStream(f);   while((b=readfile.read(temp,0,100))!=1){    String s=new String(temp,0,b);    textArea.append(s);   }   readfile.close();  }  catch(IOException e){   lab.setText("文件打开错误");  } }}Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: -1 at java.lang.String.checkBounds(Unknown Source) at java.lang.String.<init>(Unknown Source) at Test.ReadFileData.main(ReadFileData.java:29)