what si the wrong with tihs cose?????

[sheckoo]

public static String[] TakeBooksInformationfromUser() throws IOException{
int j=0;
for(int i=0;i<BooksInformation.length;i++)
if(BooksInformation[i].equals(" "))
{j=i;
break;}
else
continue;

BufferedReader in= new BufferedReader(new InputStreamReader(System.in));
inDataBook =" ";

while(inDataBook != null && j<BooksInformation.length){
System.out.print("Enter the book information withe a (,) between it ");
inDataBook=in.readLine();
BooksInformation[j]=inDataBook;
j++;
}

return BooksInformation;
}

[sheckoo]

Exception in thread "main" java.lang.NullPointerException
at booksmanagement.TakeBooksInformationfromUser(books management.java:40)

[sheckoo]

????????????????????????/
what is the problem in my code

[Fubarable]

You're trying to use an object before initializing it. You must fill the array with viable objects before you can try to call any methods on them.

[sheckoo]

i did it but what is the problem now???

import java.io.*;
public class booksmanagement {

private static String [] BooksInformation = new String[100];
public booksmanagement(){
for(int x=0; x<BooksInformation.length;x++)
BooksInformation[x]=null;
}
private static String inDataBook;

//method to load from the file into the array

public static String[] LoadBooksInFormation() throws IOException{

BufferedReader in=new BufferedReader(new FileReader("C:\\Users\\VooDoo\\Desktop\\LibrarySys tem\\books.txt"));

String read;
int m=0;
while((read = in.readLine()) != null && m<BooksInformation.length){

for(int i=0 ;i<BooksInformation.length;i++){
BooksInformation[i]=read;
}
m++;
}
in.close();
return BooksInformation;
}


// method to take data from the user and write it in the array and the file
public static String[] TakeBooksInformationfromUser() throws IOException{
int j=0;
for(int i=0;i<BooksInformation.length;i++){
if(BooksInformation[i].equals(null))
{j=i;
break;}
else
continue;
}
BufferedReader in= new BufferedReader(new InputStreamReader(System.in));
inDataBook="";

while((inDataBook != null )&&( j<BooksInformation.length)){
System.out.println("Enter the book information withe a (,) between it ");
inDataBook=in.readLine();
BooksInformation[j]=inDataBook;

BufferedWriter out= new BufferedWriter(new FileWriter("C:\\Users\\VooDoo\\Desktop\\LibrarySys tem\\books.txt",true));
out.write(inDataBook+"\n");
out.close();

j++;
}

return BooksInformation;
}

}

[CJSLMAN]

... and error yuo're getting now would be ....?

[sheckoo]

the program gives me an infinite loop for the last while

while((inDataBook != null )&&( j<BooksInformation.length))

[CJSLMAN]

use println() to see what is happening to the values in program and that way check the logic.

Luck,
CJSL

[sheckoo]

thanx i will sea what is the problem now

[sheckoo]

the problem is still exist and i dont know what to do please would u please to trace it and tell me why it dont get out from the loop

[emceenugget]

either inDataBooks is never set to null, or j is never incremented. find out which one it is, then find out why either statement isn't fulfilled, meaning pay attention to the one line of code where the variable is modified and research the methods and objects used to update your variable. =)

[CJSLMAN]

What did the println()'s show when you used them in your program to trace the flow of the data?

CJSL