Answer to a StackOverflow comment

RawUseOfGenericInterface.java

import java.util.Comparator;

// https://stackoverflow.com/questions/62122965/how-to-resolve-raw-use-of-parameterized-class-comparable-warning/62122994#62122994
public class Main {
    interface FooInt extends Comparable<Object> {
        int getInt();

        @Override
        default int compareTo(Object that) {
            if (that instanceof Number) return Integer.compare(getInt(), ((Number) that).intValue());
            if (that instanceof FooInt) return Integer.compare(getInt(), ((FooInt) that).getInt());
            throw new IllegalArgumentException("Unsupported type: " + that.getClass().getName());
        }
    }

    interface FooString extends Comparable<Object> {
        String getString();

        @Override
        default int compareTo(Object that) {
            final Comparator<String> naturalOrder = Comparator.naturalOrder();
            if (that instanceof CharSequence) return naturalOrder.compare(getString(), ((CharSequence) that).toString());
            if (that instanceof FooString) return naturalOrder.compare(getString(), ((FooString) that).getString());
            throw new IllegalArgumentException("Unsupported type: " + that.getClass().getName());
        }
    }

    static class Bar implements FooInt {
        @Override
        public int getInt() {
            return 10;
        }
    }

    static class Baz implements FooInt {
        @Override
        public int getInt() {
            return 12;
        }
    }

    static class FooBar implements FooString {
        @Override
        public String getString() {
            return "FooBar";
        }
    }

    static <T extends Comparable<Object>> T findMax(T ... items) {
        T max = items[0];
        for (T item : items)
            if (item.compareTo(max) > 0)
                max = item;
        return max;
    }

    public static void main(String[] args) {
        findMax(new Bar(), new Baz(), new FooBar()); // throws
    }
}