What is the difference between these two statements in Java?

Question

int[] X = {1,2,3}; 
int[] Y = new int[] {1,2,3}

Will the content of array X also be stored on heap?

Answer 1

The only difference is that the first statement works only when the array variable is declared, while the second can be written separately from the declaration :

int[] X;
int[] Y;
X = {1,2,3}; // doesn't work
Y = new int[] {1,2,3}; // works

Answer 2

These two statements are technically grammatically different but have identical effects.

An array initializer can appear as part of a local variable declaration initializer as in:

int[] X = {1,2,3};

and also an array creation expression as in:

new int[] {1,2,3}

And yes, X will be on the heap. All objects in Java are on the heap and since arrays are objects, all arrays are on the heap.

Answer 3

Java provides a ease of initializing arrays. So with out new operator you can directly assign value. Like

 int[] X={1,2,3};

Here the size of array is know by no.of elements in the initialization block.

Another way of initializing is using new operator.

int[] y=new int[]{1,2,3};

String variable also uses the both the way of initialization. But in Strings these two types have different meaning.