Question

I am getting null-exception throw error in the following code. What can be the reason for it?

 public static String[] CreateVocab(BufferedReader buffR) throws IOException{
    String[] arr = null;
    int i = 0;
    arr[i]= null;
    String line = new String();
    while((line = buffR.readLine()) != null){
        arr[i] = line;
        i=i+1;
    }
    return arr;     
}

Compiler is showing Null ponter exception in the code
arr[i]=null.

Answer 1

You haven’t created the array – and an array won’t solve your problem anyway, because it can’t resize. We don’t know the number of lines in advance.

Use a collection instead:

public static String[] CreateVocab(BufferedReader buffR) throws IOException{
    List<String> lines = new ArrayList<String>();
    String line = null;
    while((line = buffR.readLine()) != null){
        lines.add(line);
    }
    return lines.toArray(new String[]{});     
}