Compare two arrays

For primitive type: Arrays.equals(a1,a2)

For reference type: Arrays.deepEquals(a1,a2)

How to compare array contents?

A simple way is to run a loop and compare elements one by one.

Java provides a direct method Arrays.equals() to compare two arrays.

Actually, there is a list of equals() methods in Arrays class for different primitive types (int, char, ..etc) and one for Object type (which is base of all classes in Java).

import java.util.Arrays;

class ArraysCompare {

       public static void main (String[] args) {

              int arr1[] = {1, 2, 3};

              int arr2[] = {1, 2, 3};

              if (Arrays.equals(arr1, arr2)) {

                     System.out.println("Same");

              } else {

                     System.out.println("Not same");

              }

       }

}

Output:

Same

Issue with the equals() method:

import java.util.Arrays;

class ArraysCompare {

       public static void main (String[] args) {

              // inarr1 and inarr2 have same values

              int inarr1[] = {1, 2, 3};

              int inarr2[] = {1, 2, 3};  

              Object[] arr1 = {inarr1}; //arr1 contains only one element

              Object[] arr2 = {inarr2}; //arr2 also contains only one element

              if (Arrays.equals(arr1, arr2)) { //will not work for reference.

                     System.out.println("Same");

              } else {

                     System.out.println("Not same");

              }

       }

}

Output:

Not Same

If the arrays contain arrays inside them or some other references which refer to different object but have same values.

import java.util.Arrays;

class ArraysCompare {

       public static void main (String[] args) {

              // inarr1 and inarr2 have same values

              int inarr1[] = {1, 2, 3};

              int inarr2[] = {1, 2, 3};  

              Object[] arr1 = {inarr1};//arr1 contains only one element

              Object[] arr2 = {inarr2};//arr2 also contains only one element

              if (Arrays.deepEquals(arr1, arr2)) {

                     System.out.println("Same");

              } else {

                     System.out.println("Not same");

              }

       }

}

Output:

Same