Arrays.deepEquals() in Java with Examples

Last Updated : 25 Nov, 2024

Arrays.deepEquals() method comes under the Arrays class in Java. It is used to check two arrays, whether single-dimensional or multi-dimensional, are equal or not. It compares arrays element by element, even when dealing with nested arrays.

Example:

Below is a simple example that uses Arrays.deepEquals() to check if two multidimensional arrays are equal.

Java

import java.util.Arrays;

public class ArraysDeepEquals {
  
    public static void main(String[] args) {
        
        // three 2D integer arrays for comparison
        int[][] arr1 = { {1, 2}, {3, 4} };
        int[][] arr2 = { {1, 2}, {3, 4} };
        int[][] arr3 = { {5, 6}, {7, 8} };

        // Compare arr1 and arr2
        System.out.println("arr1 equals with arr2: " + Arrays.deepEquals(arr1, arr2)); 

        // Compare arr2 and arr3 
        System.out.println("arr2 equals with arr3: " + Arrays.deepEquals(arr2, arr3)); 
    }
}

Output

arr1 equals with arr2: true
arr2 equals with arr3: false

Table of Content

Syntax of Arrays.deepEquals() method
Examples of Arrays.deepEquals() in Java

Using Arrays.deepEquals() with Multidimensional Arrays of Integers
Using Arrays.deepEquals() with Arrays of User-Defined Objects

Syntax of Arrays.deepEquals() method

public static boolean deepEquals(Object[] o1, Object[] o2)

Parameter:

o1: This is the first array to test for equality.
o2: This is the second array to test for equality.

Return Type: It returns true, if the two arrays are deeply equal (all elements and nested arrays are equal), otherwise it will return false.

Examples of Arrays.deepEquals() in Java

Using `Arrays.deepEquals()` with Multidimensional Arrays of Integers

In this example, we will check if two-dimensional arrays of integers are equal at all levels using Arrays.deepEquals().

Java

// Java program to demonstrate working of 
// Arrays.deepEquals() with integer arrays
import java.util.Arrays;

public class GFG {
    public static void main(String[] args) {
      
        int a1[][] = { { 10, 20 },
                       { 30, 40 },
                       { 50, 60 } };

        int a2[][] = { { 50, 60 },
                       { 10, 20 },
                       { 30, 40 } };

        int a3[][] = { { 10, 20 },
                       { 30, 40 },
                       { 50, 60 } };


        // Check if a1 and a2 are equal
        System.out.println("a1 is equal to a2: " + Arrays.deepEquals(a1, a2));

        // Check if a2 and a3 are equal
        System.out.println("a2 is equal to a3: " + Arrays.deepEquals(a2, a3));

        // Check if a1 and a3 are equal
        System.out.println("a1 is equal to a3: " + Arrays.deepEquals(a1, a3));
    }
}

Output

a1 is equal to a2: false
a2 is equal to a3: false
a1 is equal to a3: true

Using `Arrays.deepEquals()` with Arrays of User-Defined Objects

In this example, we will check if arrays of user-defined Employee objects are equal by overriding the equals() method to define the equality of different parameters in a user-defined class.

Java

// Java program to demonstrate working of 
// Arrays.deepEquals() 
// with arrays of user-defined objects
import java.util.Arrays;

public class ArraysDeepEquals2 {
  public static class Employee {
        
        int i;
        String n;

        public Employee(int i, String n) {
            this.i = i;
            this.n = n;
        }

        // Override equals() to define equality 
        // based on id and name
        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;
            Employee e = (Employee) o;
            return i == e.i && n.equals(e.n);
        }
    }

    public static void main(String[] args) {
        Employee e1[][] = { { new Employee(10, "Geek1"),
                              new Employee(11, "Geek2") },
                            { new Employee(12, "Geek3"),
                              new Employee(13, "Geek4") } };

        Employee e2[][] = { { new Employee(10, "Geek1"),
                              new Employee(11, "Geek2") },
                            { new Employee(12, "Geek3"),
                              new Employee(13, "Geek4") } };

        Employee e3[][] = { { new Employee(12, "Geek2"),
                              new Employee(25, "Geek4") },
                            { new Employee(15, "Geek3"),
                              new Employee(30, "Geek1") } };

        // Check if e1 and e2 are equal
        System.out.println("e1 is equal to e2: " + Arrays.deepEquals(e1, e2));

        // Check if e2 and e3 are equal
        System.out.println("e2 is equal to e3: " + Arrays.deepEquals(e2, e3));

        // Check if e1 and e3 are equal
        System.out.println("e1 is equal to e3: " + Arrays.deepEquals(e1, e3));
    }
}

Output

e1 is equal to e2: true
e2 is equal to e3: false
e1 is equal to e3: false

Equals() vs deepEquals()

Arrays.equals() method works correctly on an single dimensional array, but it cannot check the equality of a multidimensional array.
Arrays.deepEquals() method works on all arrays irrespective of the dimension.

Introduction to Java

Sumit Ghosh

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Java

Arrays.deepEquals() in Java with Examples

Syntax of Arrays.deepEquals() method

Examples of Arrays.deepEquals() in Java

Using Arrays.deepEquals() with Multidimensional Arrays of Integers

Using Arrays.deepEquals() with Arrays of User-Defined Objects

Equals() vs deepEquals()

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Using `Arrays.deepEquals()` with Multidimensional Arrays of Integers

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