If two arrays are equal, then a mismatch should return -1. But if two arrays are not equal, then a mismatch should return the index of the first mismatch between the two given arrays. In order to resolve this problem, we can rely on JDK 9 Arrays.mismatch() methods.

For example, we can check for mismatches between integers1 and integers2 as follows:

int mi12 = Arrays.mismatch(integers1, integers2); // -1

The result is -1, since integers1 and integers2 are equal. But if we check for integers1 and integers3, we receive the value 5, which is the index of the first mismatch between these two:

int mi13 = Arrays.mismatch(integers1, integers3); // 5

For arrays of Object, there are dedicated mismatch() methods as well. These methods count on the equals() contract or on the given Comparator. We can check whether there is a mismatch between melons1 and melons2 as follows:

int mm12 = Arrays.mismatch(melons1, melons2); // -1

If the mismatch occurs on the first index, then the returned value is 0. This is happening in the case of melons1 and melons3:

int mm13 = Arrays.mismatch(melons1, melons3); // 0

As in the case of Arrays.equals(), we can check mismatches in an explicit range using a Comparator:

// range [1, 2), return -1
int mms13 = Arrays.mismatch(melons1, 1, 2, melons3, 1, 2);

// Comparator by melon's weights, return -1
int mmw13 = Arrays.mismatch(melons1, melons3, byWeight);

// Comparator by melon's types, return 0
int mmt13 = Arrays.mismatch(melons1, melons3, byType);

// range [1,2) and Comparator by melon's types, return -1
int mmrt13 = Arrays.mismatch(melons1, 1, 2, melons3, 1, 2, byType);