Question

I am trying to implement generics in Java using Comparable<T> interface.

public static <T> T[] sort(T[] a) {
    //need to compare 2 elements of a
}

Let’s say, I want to override the compareTo method for the above type T in the Comparable interface. I.e. I need to compare two elements of my type T, how will I do it? I don’t know what my T type will be.

Answer 1

You need to set a type constraint on your method.

public static <T extends Comparable<? super T>> T[] sort (T[] a)
{
         //need to compare 2 elements of a
}

This forces the type T to have the compareTo(T other) method. This means you can do the following in your method:

if (a[i].compareTo(a[j]) > 0) }

}