java.lang.NullPointerException异常解决方法!

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？

------解决方法--------------------------------------------------------
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
------解决方法--------------------------------------------------------
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
------解决方法--------------------------------------------------------
FileReader fr = new FileReader( "d:/java/1.txt ");;
BufferedReader br = new BufferedReader(fr);