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javaarraysjava-7hashcode

How to use Java 7+ 'Objects.hash()' with arrays?

I really like Java 7+ style of writing hashCode() method:

@Override
public int hashCode() {
    Objects.hash(field1, field2);
}

It doesn't work correctly with arrays though. The following code:

@Override
public int hashCode() {
    Objects.hash(field1, field2, array1, array2);
}

will not work, as for array1 and array2 regular hashCode() instead of Arrays.hashCode() would be invoked.

How can I use Objects.hash() with arrays in a proper way?

Solution

  • You could try:

    Objects.hash(field1, field2, Arrays.hashCode(array1), Arrays.hashCode(array2));

    This is the same as creating one array that contains field1, field2, the contents of array1 and the contents of array2. Then computing Arrays.hashCode on this array.