collections - Implement both Map and List interface in Java?

Question

I'd like to have an object that implements both the Map and the List interfaces in Java. The idea is similar to the problem in this question: Java Ordered Map

I want to add name/value pairs to a list and have the list preserve the sequence, but also be able to do lookups by name:

foo.put("name0", "value0");
foo.put("name1", "value1");
foo.get(1); --> Map.Entry("name1", "value1")
foo.get("name0"); --> "value0"

Here's the problem: when I create this class:

class Foo implements Map, List {
    // add all methods here
}

I get a compile error:

"The return type is incompatible with Map.remove(Object)"
public boolean remove(Object o) {
    return false;
}

If I don't implement the Map and List interfaces, then there are lots of Java collections methods that aren't available to use on this data structure.

(Also, the reason that the solution proposed in Java Ordered Map above doesn't work is that LinkedHashMap doesn't have a get(int) method. Can't select entries by index.)

Answer 1

It should be pointed out that the reason for the error is that Map contains the definition for the following remove method:

V remove(Object key)

While List defines:

boolean remove(Object o) 

And, in Java, methods cannot be overloaded based on their return type, so they are conflicting signatures, and cannot be implemented in the same class.