making elements of an array null

Question

are these two the same things?

for(int i=0; i<array.length; i++){
array[i] = null;
}

and

array = null;

Answer 1

Neither of them will work! If you have an array of integers and you try to make an element null you can't do arr[i]=null; because integer cannot be converted to null.

Answer 2

A small snippet to show the difference:

// declare a array variable that can hold a reference.
String [] array;

// make it null, to indicate it does not refer anything.
array = null;

// at this point there is just a array var initialized to null but no actual array.

// now allocate an array.
array = new String[3];

// now make the individual array elements null..although they already are null.
for(int i=0;i<array.length;i++)
{
    array[i] = null;
}
// at this point we have a array variable, holding reference to an array, 
// whose individual elements are null.

Answer 3

No, the first one makes each element of the array null, the length of the array will still be array.length, the second will set the array variable to null.

Answer 4

No, it is not the same.

As a matter of fact, for the first snippet of code to run correctly, the array variable should be declared and initialized like this (for example)

Object[] array = new Object[5];

This creates an array of 5 elements with each element having a null value.

Once you have this, in the first example what you are doing is assigning a null value to each of the array[i] elements. array will not be null. So you should have something like this.

array ->

• array[0] -> null
• array[1] -> null
• array[2] -> null
• array[3] -> null
• array[4] -> null

By doing array = null you are saying that the array no longer references that array of elements. Now you should have

array -> null