In this example, we will explain the array definition and we will show the range of functionality provided by the Java arraysclass: java.util.Arrays. This class of thejava.util package contains several static methods that you can use to compare, sort, and search in arrays. In addition, you can use this class to assign a value to one or more elements of an array. This class is a member of theCollections Framework.

An array of integers (int[]) will be used as our base array in the following example to illustrate most of the methods provided by the java.util.Arraysclass. But before diving into the practical examples, let us understand the different types that are available in the Java programming language.

You can also check this tutorial in the following video:

• One-Dimensional Arrays: The type that consists of the array type and name. The array type will determine the type of array and the elements will determine the type of element inside the array. Let us understand the declaration of One-D arrays with an example.

  1 2 3 4 5

  int[] arr1  // A one-dimensional array of integer elements. String[] arr2   // A one-dimensional array of string elements. float[] arr3    // A one-dimensional array of floating-point elements.   Object[] arr4   // A one-dimensional array of object elements. This array can either consist of mixture of primitive type elements or secondary elements.

• Multi-Dimensional Arrays: It is an array of arrays where each element holds a reference of another array. These types of arrays are also called Jagged Arrays and are defined in the following manner. Let us understand the declaration of Two-D arrays with an example.

  1 2	int[][] arry1 = newint[10][20];    //a 2D array or matrix int[][][] arr2 = newint[10][20][10];   //a 3D array

  Please note, these days the IT industry has obsolete the use of multi-dimensional arrays due to the extensive use of collections.

• Array Literals: These are used in a situation where the array size and variables are known. Let us understand the declaration of Array Literals with an example.

  1	int[] intArray = newint[]{ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10};   // Declaring array literal

  In this, the array length is automatically determined by the number of elements.

But let’s examine the array definition, by using the following examples.

1. Example of Java Arrays methods

Now let us start with an example to understand the basic declaration and different methods inArrays. But before digging deep let us look at different methods we will be using in this example.

1.1 Arrays.toString() method

Thismethod returns the String representation of the array enclosed in the square brackets ([]). Adjacent elements are separated by the comma character (i.e.a comma followed by a space). Let us understand this with a simple example.

Snippet

1.2 Arrays.asList() method

Thismethod returns a list backed by a given array. In other words, both the list and array refer to the same location. Let us understand this with a simple example.

Snippet

1.3 Arrays.sort() method

Thismethod sorts the specified array into ascending numerical order. Let us understand this with a simple example.

Snippet

1.4 Arrays.binarySearch() method

Thismethod returns an integer value for the index of the specified key in the specified array. Return a negative number if the key is not found and for this method to work properly, the array must be sorted. Let us understand this with a simple example.

Snippet

1.5 Arrays.copyOf() method

Thismethod copies the specified array, truncates or pads with zeros (if necessary) so the copy has the specified length. Let us understand this with a simple example.

Snippet

1.6 Arrays.copyOfRange() method

Thismethod copies the specified range of the specified array into a new array. The initial index of the range (from) must lie between zero and original.length, inclusive. Let us understand this with a simple example.

Snippet

1.7 Arrays.fill() method

Thismethod fills all elements of the specified array with the specified value. Let us understand this with a simple example.

Snippet

1.8 Complete Example

Let us consider the below example where we will illustrate all the methods explained above.

JavaUtilArraysExample.java

If everything goes well, we will get the following results in the console.

2. Some more methods of the Java Array class

Java Arrays add some interesting method arguments to the existingsort() andfill() method i.e.

• Arrays.sort(int[] a, int fromIndex, int endIndex): Sorts the specified range of the array into ascending order. The range to be sorted extends from the indexfromIndex, inclusive, to the indextoIndex, exclusive. IffromIndex ==toIndex, the range to be sorted is empty
• Arrays.fill(int[] a, int fromIndex, int endIndex): Fills elements of the specified array with the specifiedvalue from thefromIndex element, but not including thetoIndex element

Let us understand these modifications with an example.

JavaUtilArraysMoreMethodsExample.java

If everything goes well, we will get the following results in the console.

3. More articles

• Java List Example
• Java Queue Example
• Java Stack Example
• ArrayList Java Example – How to use arraylist

4. Download the Source Code

That was an article explaining the array definition in Java through examples.

Last updated on Jan. 25th, 2022

Do you want to know how to develop your skillset to become aJava Rockstar?

Subscribe to our newsletter to start Rockingright now!

To get you started we give you our best selling eBooks forFREE!

1. JPA Mini Book

2. JVM Troubleshooting Guide

3. JUnit Tutorial for Unit Testing

4. Java Annotations Tutorial

5. Java Interview Questions

6. Spring Interview Questions

7. Android UI Design

and many more ....

I agree to theTerms andPrivacy Policy

Sign up

Thank you!

We will contact you soon.