public File[] getFolderFile2()
    {
        File dir = new File("");
        String sb =dir.getAbsolutePath();
        File sub = new File(sb);
        File []files = sub.listFiles();
        File [] newFile= new File[10];
        for(int i=0,j=0; i<files.length; i++ )
        {
          if(files[i].isFile())
           {
                String name =files[i].getName();
                int point =name.lastIndexOf(".");
                String rightPart=name.substring(point,name.length());
              if(rightPart.equals(".bak"))
             {
              //    System.out.println(files[i]);
              //    System.out.println("1231");
                     newFile[j++]=files[i];
                       
               //      System.out.println(newFile[j]);
               }    
                 
              
          }
        }
        return newFile;
        
    } 
    


    public void changeContent2(File[] paramArrayOfFile)
    {
        String str;
        for (int i = 0; i < paramArrayOfFile.length; i++)
        {
            System.out.println(paramArrayOfFile[i]);
              try
              {
                    BufferedReader localBufferedReader = new BufferedReader(new FileReader(paramArrayOfFile[i]));
                   BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(paramArrayOfFile[i].getName()+".bak")));
                
                StringBuffer  sb = new StringBuffer();
                while((str=localBufferedReader.readLine())!=null)
                {
                    sb.append(str);
                    int index=0;
                    while((index=sb.indexOf(Session,index))!=-1)
                    {
                        sb.replace(index,index+Session.length(),sessionTF.getText().trim());
                        index+=(sessionTF.getText()).length();
                    }
                    
                    bw.write(sb.toString(),0,sb.length());
                    bw.newLine();
                    sb.delete(0,sb.length());
                } 
                
                localBufferedReader.close(); 
                bw.flush(); 
                bw.close();

              }catch (IOException localIOException)
                  {
                    System.out.println(localIOException);
                  }
        }
    } 
    


会出现下面错误

D:\programming\java\createBoot\AUTOEXEC.txt.bak
D:\programming\java\createBoot\PROTOCOL.txt.bak
D:\programming\java\createBoot\SYSTEM.txt.bak
null
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
        at java.io.FileInputStream.<init>(FileInputStream.java:103)
        at java.io.FileReader.<init>(FileReader.java:55)
        at CreateBoot.changeContent2(CreateBoot.java:335)
        at CreateBoot.actionPerformed(CreateBoot.java:174)
        at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:19
95)
        at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.jav
a:2318)
        at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel
.java:387)
        at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242
)
        at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonL
istener.java:236)