Arrays Class in Java

The Arrays class in the java.util package is a utility class that provides a collection of static methods for performing common operations on Java arrays, such as sorting, searching, comparing and converting arrays to strings.
It does not extend any special classes like all Java classes, it implicitly extends Object. The Arrays class itself cannot be instantiated and is designed solely for utility purposes.

Why do we need the Java Arrays class

Java provides a utility class called java.util.Arrays to help developers perform common array operations easily and efficiently. like:

• Fill an array with a particular value.
• Sort an array
• Search in an array
• And many more

Class Declaration  

Arrays is a final utility class in java.util package that extends Object class, which is the root of the Java class hierarchy

public class Arrays extends Object

To use Arrays,

Arrays.<function name>;
Arrays.sort(array_name);

Methods in Java Array Class 

The Arrays class of the java.util package contains several static methods that can be used to fill, sort, search, etc in arrays. Let's take a look at methods and their implementation:

1. asList() method.

This method converts an array into a list.

import java.util.Arrays;

class Geeks{
  
    public static void main(String[] args){
        // Get the Array
        int intArr[] = { 10, 20, 15, 22, 35 };

        // To convert the elements as List
        System.out.println("Integer Array as List: "
                           + Arrays.asList(intArr));
    }
}

Integer Array as List: [[I@19469ea2]

Note: When asList() is used with primitive arrays, it shows the memory reference of the array instead of the list contents. This happens because the asList() method returns a fixed-size list backed by the original array, and for primitive types like int[], it treats the array as an object, not as a list of values.

2. binarySearch() Method

This methods search for the specified element in the array with the help of the binary search algorithm.

import java.util.Arrays;

public class Geeks {

    public static void main(String[] args){

        // Get the Array
        int intArr[] = { 10, 20, 15, 22, 35 };

        Arrays.sort(intArr);

        int intKey = 22;

        // Print the key and corresponding index
        System.out.println(
            intKey + " found at index = "
            + Arrays.binarySearch(intArr, intKey));
    }
}

22 found at index = 3

3. binarySearch(array, fromIndex, toIndex, key, Comparator) Method 

This method searches a range of the specified array for the specified object using the binary search algorithm.

import java.util.Arrays;

public class Main {
    public static void main(String[] args)
    {

        // Get the Array
        int intArr[] = { 10, 20, 15, 22, 35 };

        Arrays.sort(intArr);

        int intKey = 22;

        System.out.println(
            intKey
            + " found at index = "
            + Arrays
                  .binarySearch(intArr, 1, 3, intKey));
    }
}

22 found at index = -4

4. compare(array 1, array 2) Method 

This method returns the difference as an integer lexicographically.

import java.util.Arrays;

public class Main {
    public static void main(String[] args)
    {

        // Get the Array
        int intArr[] = { 10, 20, 15, 22, 35 };

        // Get the second Array
        int intArr1[] = { 10, 15, 22 };

        // To compare both arrays
        System.out.println("Integer Arrays on comparison: "
                           + Arrays.compare(intArr, intArr1));
    }
}

Integer Arrays on comparison: 1

Below table contains list of all methods:

Arrays Class in Java

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