Header javaperspective.com
JavaPerspective.com  >   Beginner Tutorials  >   3. Java Basics  >   3.8. Java arrays

3.8. Java arrays
Last updated: 23 January 2013.

An array is a variable which contains multiple values of the same type. An array has a fixed size that can't be changed after the array is created. The sample below declares an array of integers:

int[] myArray;

At this point, no memory is allocated to the array. To allocate memory to the array, you need to use the keyword new as shown below:

myArray = new int[5];

The above statement allocates enough memory for an array of 5 integers. The two statements above can be merged into a single statement:

int[] myArray = new int[5];

The initialization of the array elements can now be done this way:

myArray[0] = 1;
myArray
[1] = 2;
myArray
[2] = 3;
myArray
[3] = 4;
myArray
[4] = 5;

As you can see, the index of the first element is 0 and the index of the last element is 4. In Java, array indexes start at 0.

You can also declare, allocate memory and initialize an array in a single statement like this:

int[] myArray = {1, 2, 3, 4, 5};

The code below prints all of the array elements to the standard output:

System.out.println(myArray[0]);
System.out.println
(myArray[1]);
System.out.println
(myArray[2]);
System.out.println
(myArray[3]);
System.out.println
(myArray[4]);

The output is:

1
2
3
4
5


myArray.length gives you the size of the array. If you execute this line of code:

System.out.println(myArray.length);

You will get this output:

5



In the Java language, multidimensional arrays are declared as arrays of arrays:

int[][] myArray = new int[3][5];

myArray
[0] = new int[]{1, 2, 3, 4, 5};
myArray
[1] = new int[]{11, 22, 33, 44, 55};
myArray
[2] = new int[]{111, 222, 333, 444, 555};

System.out.println
(myArray[0][0]);
System.out.println
(myArray[1][2]);
System.out.println
(myArray[2][4]);

The output is:

1
33
555


You are here :  JavaPerspective.com  >   Beginner Tutorials  >   3. Java Basics  >   3.8. Java arrays
Next tutorial :  JavaPerspective.com  >   Beginner Tutorials  >   3. Java Basics  >   3.9. The if-else statement

Copyright © 2013 - 2016. JavaPerspective.com. All rights reserved.  ( Terms | Contact | About ) 
Java is a trademark of Oracle Corporation
Image 1 Image 2 Image 3 Image 4 Image 5 Image 6 Image 7