Java Arrays

An array is a group of variables of similar types that are referred to by a common name. Arrays of any type can be created and may have one (single dimensional arrays) or more dimensions (multidimensional arrays). A specific element in an array is accessed by its index. Arrays offers a convenient means of grouping the related information.

Types of Arrays in Java

There are following two types of arrays in Java:

Declare Array in Java

Here is the general form to declare an array in Java:

type array-name[];

Here, type represents the element type (also called as the base type) of the array named array-name. Here is an example, declaring an array named arr of type int:

int arr[];

Alternative Array Declaration in Java

There is also a second form to declare an array:

type[] var-name;

Here, the square brackets come after the type specifier, and not the same of the array variable. For example, the following two declarations are equivalent:

int arr1[] = new int[3];
int[] arr1 = new int[3];

And the following two declaration are also equivalent (you will learn about multidimensional array in upcoming chapter):

char twodim1[][] = new char[3][4];
char[][] twodim1 = new char[3][4];

The alternative declaration form, offers convenience when declaring several arrays at the same time. For example :

int[] arrs, arr2, arr3;    // create three arrays

creates three array variables of type int. It is same as writing:

int arrs[], arr2[], arr3[];    // create three arrays

The alternative declaration form is also useful when specifying an array as a return type for a method.

Java Arrays Example

Here is an example, illustrates the concept and use of arrays in Java:

/* Java Arrays - Example Program */
public class JavaProgram
    public static void main(String args[])
        int arr[] = new int[10];
        int i;
        // initializing values to array's elements
        for(i=0; i<10; i++)
            arr[i] = i;
        // printing back, all the values of array
        for(i=0; i<10; i++)
            System.out.println("arr[" + i + "] = " + arr[i]);

Here is the sample output of the above Java Program:

arrays in java example

Here is another program in Java, helps in understanding the arrays in Java:

/* Java Program Example - Java Arrays */
 public class JavaArray
   public static void main(String[] args)
      double[] arr = {1.9, 2.9, 3.4, 3.5};
      double tot = 0;

      for(int i=0; i < arr.length; i++)
         System.out.println(arr[i] + " ");
      for(int i=0; i < arr.length; i++)
         tot = tot + arr[i];
      System.out.println("Total is " + tot);
      double maxm = arr[0];
      for(int i=1; i < arr.length; i++)
         if (arr[i] > maxm)
            maxm = arr[i];
      System.out.println("Max is " + maxm);

Here is the output produced by the above Java program:

java arrays

More Examples

Here are some examples related to arrays, you can go for.

You will learn about one dimensional arrays and multidimensional arrays from next chapter.

Java Online Test

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