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:

• One Dimensional Arrays
• Multidimensional Arrays

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:

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:

More Examples

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

• One Dimensional Array Program
• Linear Search
• Binary Search
• Three Dimensional Array Program

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

Java Online Test