一个奇怪的runtimeException解决方法

一个奇怪的runtimeException
import   java.io.*;
public   class   TestTransForm1   {
    public   static   void   main(String[]   args){
    FileReader   fr   =   null;
    BufferedReader   br   =   new   BufferedReader(fr);
   
    try   {
fr   =   new   FileReader( "d:/java/1.txt ");
}   catch   (FileNotFoundException   e)   {
//   TODO   Auto-generated   catch   block
e.printStackTrace();
}
   
    String   str   =   null;
   
    try   {
while((str=br.readLine())!=null){
    System.out.println(str);
    }
   
    br.close();
   
    fr.close();
}   catch   (IOException   e)   {
//   TODO   Auto-generated   catch   block
e.printStackTrace();
}
    }
}

报错：Exception   in   thread   "main "   java.lang.NullPointerException
at   java.io.Reader. <init> (Unknown   Source)
at   java.io.BufferedReader. <init> (Unknown   Source)
at   java.io.BufferedReader. <init> (Unknown   Source)
at   TestTransForm1.main(TestTransForm1.java:5)
文件有内容，而且同样的程序我有时候执行就没问题，请问这种情况问题是出在哪里了？

------解决方案--------------------
FileReader fr = null;
BufferedReader br = new BufferedReader(fr);
fr是null,现在又把它当作流来包装,它应该还没给内存啊
------解决方案--------------------
FileReader fr = null;
BufferedReader br = new BufferedReader(fr);

try {
fr = new FileReader( "d:/java/1.txt ");
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
这段这样改
FileReader fr = null;
BufferedReader br = null;

try {
fr = new FileReader( "d:/java/1.txt ");
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
br = new BufferedReader(fr);
这样试试
------解决方案--------------------
FileReader fr = new FileReader( "d:/java/1.txt ");;
BufferedReader br = new BufferedReader(fr);