- This step creates an actual array object on the heap memory with the specified size i.e.) number of elements this array will hold.
- Size must be a positive integer value.
- This is done using new keyword/operator.
- This step is also known as instantiating an array, creating an array object, allocating memory space.
One dimensional array
double[] studentAvgs; //declaring an array reference studentAvgs = new double[5]; //creating an array object or allocates memory for 5 elements
The preceding code creates a new array object on the heap holding five elements – with each element being a double with a default value 0.0
You can also declare and instantiate in a single statement.
double[] studentAvgs = new double[5]; //declare & allocate an array object
for example, the fifth element would be accessed at index 4.
Multidimensional array
A two dimensional array is simply an array object with each element in the array being a reference to another array.
Method 1:
double[][] studentAvgs; //declaring an array reference studentAvgs = new double[3][]; //creating an array object
You can also declare and instantiate a two dimensional array in a single statement.
double[][] studentAvgs = new double[3][];
Method 1 creates three rows and each row can hold any number of elements which can be defined later.
Method 2:
double[][] studentAvgs; //declaring an array reference studentAvgs = new double[3][2]; //creating an array object
You can also declare and instantiate a two dimensional array in a single statement.
double[][] studentAvgs = new double[3][2];
Method 2 creates three rows and each row referring to an array of two elements.
When creating a two dimensional array, you must provide row size.
double[][] studentAvgs = new double[][]; //ERROR
