Please Help with BufferedReader class. Thanks.

[markospolo]

Hi everyone would someone please help me with bufferedReader class i am having
problems with it. it trows some nullPointer Exception at me. here is my code.
It compiles with no errors but gives an error in run. I'd like just go get
a tip how i can avoid that error with not much change to what i do because
i am just starting. Thanks.

import java.io.*; class arrayGrades {


BufferedReader s;

public arrayGrades() throws IOException{

//System.out.println("Object arrayGrades created");

BufferedReader s= new BufferedReader(new InputStreamReader(System.in));

}

private String sStudent () throws IOException {

//String s = System.in.read String v="";
System.out.println("Please Enter Students Name");

v = (String)s.readLine();
System.out.println(v);


return v; }

private String sGrade () throws IOException{

return "33";

}

public static void main (String args [] ) throws IOException{ int i=0;

arrayGrades x = new arrayGrades();

do {

System.out.println(x.sStudent()); x.sGrade();
i++;

}while (i<3); } // Main
} // class

[MarkosPolo]

Problem was solved.