Original article: Java: Testing array equality

Two arrays are equal if all their values are equal and in the same order.



# Arrays.equals()

The **`Arrays.equals`** method can be used to check if two arrays are equal.

This method takes two arrays as arguments.


import java.util.Arrays;

class ArrayEquality {
    public static void main( String args[] ) {
        int [] arr1 = new int [] {20, 5, -95, 43, 17};
        int [] arr2 = new int [] {20, 5, -95, 43, 17};
        System.out.println(Arrays.equals(arr1, arr2));
    }
}

Note that a *shallow comparison* is performed, i.e.,  it checks:
```java
arr1[0].equals(arr2[0]),
arr1[1].equals(arr2[1]),
...
```

This is *not* suitable for multidimensional arrays.

# Arrays.deepEquals()
The **`Arrays.deepEquals()`** method is a more effective way of testing the equality of multidimensional arrays.

This method takes two arrays as arguments.

import java.util.Arrays;

class ArrayEquality {
    public static void main( String args[] ) {
        int [][] arr1 = {{20, 5}, 
                         {-95, 43}, 
                         {17, 22}};
        int [][] arr2 = {{20, 5}, 
                         {-95, 43}, 
                         {17, 22}};

        System.out.println(Arrays.deepEquals(arr1, arr2));
    }
}

This method recurses on the arrays and compares the actual elements. It can be used with single-dimension arrays as well.

How to test array equality in Java

Use Arrays.equals() for single-level arrays and Arrays.deepEquals() for multi-dimensional array equality testing in Java.