Question: I've got a class using two generic parameters in its constructor. I would like to implement a method to compare two instances of this class, as done in the code below.

It works quite well except when one of the parameter is an arrays. I've read different topics about how to compare arrays with `java.util.Arrays.equals(Object[] a, Object[] a2)` but as my parameters are not defined as arrays, I can't use this method.

How could return "true" in the content of my array is the same? Or is it possible to cast my parameters to use `java.util.Arrays.equals(Object[] a, Object[] a2)`?

```
public class Pair<U, V> {

    public final U first;
    public final V second;

    public Pair(U first, V second) {
        this.first = first;
        this.second = second;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o)
            return true;
        if (o == null || getClass() != o.getClass())
            return false;

        Pair<?, ?> myPair= (Pair<?, ?>) o;

        if (!first.equals(myPair.first) || !second.equals(myPair.second))
            return false;
        return true;
    }
}

```

Answer: 
```
@Override
public boolean equals(Object o) {
    if (this == o)
        return true;
    if (o == null || getClass() != o.getClass())
        return false;

    Pair<?, ?> myPair = (Pair<?, ?>)o;

    if (first.getClass().isArray() ^ first.getClass().isArray() || second.getClass().isArray() ^ second.getClass().isArray())
        return false;
    return deepEquals(first, myPair.first) && deepEquals(second, myPair.second);
}

private static boolean deepEquals(Object one, Object two) {
    if (one instanceof byte[])
        return Arrays.equals((byte[])one, (byte[])two);
    if (one instanceof char[])
        return Arrays.equals((char[])one, (char[])two);
    if (one instanceof short[])
        return Arrays.equals((short[])one, (short[])two);
    if (one instanceof int[])
        return Arrays.equals((int[])one, (int[])two);
    if (one instanceof long[])
        return Arrays.equals((long[])one, (long[])two);
    if (one instanceof boolean[])
        return Arrays.equals((boolean[])one, (boolean[])two);
    if (one instanceof float[])
        return Arrays.equals((float[])one, (float[])two);
    if (one instanceof double[])
        return Arrays.equals((double[])one, (double[])two);
    if (one instanceof Object[])
        return Arrays.equals((Object[])one, (Object[])two);
    return one.equals(two);
}

```
You can do this:

* use the guidance given [here](https://stackoverflow.com/questions/2725533/how-to-see-if-an-object-is-an-array-without-using-reflection) to determine whether both objects (this and the "other") contain arrays. Of course, detecting the actual member type means even more work.
* utilize [Array.equals()](https://stackoverflow.com/questions/8777257/equals-vs-arrays-equals-in-java) to write specific comparison code when the fields are in fact arrays.

But make no mistake: getting your `equals()` implementation to be correct, and work with inheritance and what not ... will be a major challenge! 

For example: do you consider an array of int to be equal to a list of Integer values (assuming the values are all in fact the same)? Or what about nested arrays? 

The real point here: Java doesn't have deep equality for arrays, and it is close to impossible to cover all potential cases yourself!