Unlike primitive data types, any array has to be created using the new
operator. A reference to an array can be declared without any elements and can be assigned to null. A reference can be further modified as well.
To create an array, you first must create an array variable of the desired type. The general form of a one-dimensional array declaration is
type var-name[] = new type[desired-length];
- type tells the element type e.g.,
int
, float
- var-name gives the variable name e.g.,
student_marks
, months
- new allocates memory required for the array with the size mentioned at desired-length e.g., 5, 12
The following code creates an array of student marks for a class with 25 students. And all elements in the array are initialized to zero automatically.
int student_marks[] = new int[25];
- Arrays are allocated at run-time, hence we can use a variable to set their dimension.
int array_size = 100;
float[] my_array = new float[array_size]; // array_size should be of type byte, short or int
- You can assign an array a null value but you can't create an empty array by using a blank index.
int[] array = null; // legal
int[] array = new int[]; // illegal initialization
- The length of the array can be obtained using the
length
variable in array. This variable will be useful when iterating through the values of an array.
int[] array = new int[12];
System.out.println("Array length is " + array.length);
Accessing array elements explains about how to access the array elements
i.e. how to assign values to elements of an array and how to read them.