Puzzled with terminology (again)

Question

at some point i read this from api (NullPointerException):
is created when:
Calling the instance method of a null object.
Accessing or modifying the field of a null object.
Taking the length of null as if it were an array.
Accessing or modifying the slots of null as if it were an array.
Throwing null as if it were a Throwable value.
working on the java online tutorial i got this:
Exercise: The following program, WhatHappens, contains a bug. Find it and fix it.
// This program compiles but won't run successfully.
public class WhatHappens {
    public static void main(String[] args) {
        StringBuffer[] stringBuffers = new StringBuffer[10];
        for (int i = 0; i < stringBuffers.length; i ++) {
            stringBuffers.append("StringBuffer at index " + i);
Answer: The program generates a NullPointerException on line 6. The program creates the array, but does not create the string buffers, so it cannot append any text to them.
Well, from what i understand the array is created but each object that populates it isnt created, so each of these objects has a NULL value.
so i'm inclined to second case : (for the error msg)
Accessing or modifying the field of a null object.
My Q:
is it correct to think like this:
field means the value assigned to obj (in this case every member of array)?
thanks in advance

Answer 1

Not quite- the array consists of elements that are null. It's OK to get the value of the element, as the array isn't null- rewrite the code as public class WhatHappens {
    public static void main(String[] args) {
        StringBuffer[] stringBuffers = new StringBuffer[10];
        for (int i = 0; i < stringBuffers.length; i ++) {
            StringBuffer element = stringBuffers;
System.out.println(element);
element.append("StringBuffer at index " + i);
}And then see where the exception is thrown.
Pete