Java Array
In this chapter you will learn:
Introduction to Arrays
A Java array is an ordered collection of primitives, object references, or other arrays. Java arrays are homogeneous: except as allowed by polymorphism, all elements of an array must be of the same type.
Each variable is referenced by array name and its index. Arrays may have one or more dimensions.
One-Dimensional Arrays
A one-dimensional array is a list of similar-typed variables. The general form of a one-dimensional array declaration is:
type var-name[ ];
type declares the array type.
type also determines the data type of each array element.
The following declares an array named days with the type "array of int":
int days[];
days is an array variable.
The value of days is set to null.
Allocate memory for array
You allocate memory using new and assign it to array variables.
new is a special operator that allocates memory.
The general form is:
arrayVar = new type[size];
There are three parts in the code above.
typespecifies the type of data being allocated.sizespecifies the number of elements.arrayVaris the array variable.
The following two statements first create an int type array variable and then allocate memory for it to store 12 int type values.
int days[];
days = new int[12];
days refers to an array of 12 integers.
All elements in the array is initialized to zero.
Next chapter...
What you will learn in the next chapter:
- How to declare an array type and allocate memory
- What are the default value for different type of array
- What are Alternative Array Declaration Syntax
- How to initialize an array during the declaration