Create an array of references

If I have a class say A, and I declare an array of 10 elements of this class as,

A [] arr=new A[10];

Then 10 new objects of A are created and stored in the array.

That's not correct. Here, an array of ten references gets created, and each reference gets set to null. There are no instances of A created by this code.

In other words, the code already does exactly what you'd like it to do.

if you do A [] arr=new A[10]; then no objects are created except your array, each field will be null until you initialize it.

A [] arr=new A[10]; only create place to store reference of A Class object. Although array arr is created but its not referencing any object and you can't do like arr[i].someMethod().

To correct it, allocate object at individual memory in array do like this:

A [] arr=new A[10];
arr[0] = new A();
arr[1] = new A();
:
:

or in a loop like:

  for(i=0; i<10; i++){
      arr[i] = new A();
  }

After there arr that is an array of reference, refers to a valid A class object. And after this expression arr[i].someMethod() will not cause an error.

This is a common OOP problem and can be solved using the Null Object design pattern.

In order to not have to initialize n objects, you create a single static object of the same type for example:

public class A {
  public static final A NULL = new A();
.
.
.
}

Now this object can act as your null reference by calling:

A[] arr = new A[10];
Arrays.fill(arr, A.NULL);

Which also conveniently leverages the use of .equals and . hashCode if you want to check for nulls.