Java Arrays explained with code samples

Introduction

An array is essentially a list of values referred to by a common name. Java arrays can be one-dimensional or multi-dimensional.

Declaring and Initializing an Array

Consider the following code snippet:

int myArray[];

myArray = new int[10];

Here, int refers to the type of data that will be stored in the array and myArray is the name given to the array. In the second line myArray is allocated memory. The new keyword is used. [10] – indicates the size of the array. So this statement creates a new array with space for 10 integer values.

The declaration and memory allocation can also be combined into a single statement as follows:

int myArray[] = new int[10];

Accessing the elements of an array

Each value within the array is called an element in the array. You can access any element in an array by specifying its position within square brackets. The array index begins at 0, so the 1^st element is at position 0, the 2^nd at position 1 and so on.

Consider the following code snippet:

myArray[2] = 8;

System.out.println("Element at myArray[2]="+myArray[2]);

The element at index 2 i.e. the 3rd element in the array is assigned the value 8.  So when you execute this code, it will print the following output:

Element at myArray[2]=8

Initializing an Array at the time of declaration

Arrays can also be initialized when they are declared as follows:

int myArray[] = {2,4,6,8,10};
System.out.println("Element at myArray[3]="+myArray[3]);

Here, a list of comma-separated values surrounded by curly braces is used. Size is not specified in the square brackets explicitly; it is the same as the number of elements in the curly brackets.

When you execute this code, it will print the following output:

Element at myArray[3]=8

Obtaining the Length of an Array

There is a length method provided on the array object. This can be used to determine the size of the array.

int myArray[] = {2,4,6,8,10};
System.out.println("Size of the array is "+myArray.length);

So when this code is executed, it will print the following output:

Size of the array is 5

Conclusion

So, in this article, we understood what Java arrays are and how they can be used.