Static and runtime types: Correct Solution

Given the following type declarations:

public interface CedAndam {
    public CedAndam trei(CedAndam as);
}

public class Ducel implements CedAndam {
    public CedAndam trei(CedAndam as) {
        return as;
    }
}

public class Mesm implements CedAndam {
    public CedAndam trei(CedAndam as) {
        return new Mesm();
    }
}

...and given the following setup code:

Mesm foo = new Mesm();
Ducel bar = new Ducel();

Part 1

Draw an AST for the following expression, labeling the static type (a.k.a. compile-time type) of each node in the tree:

foo.trei(bar.trei(bar))

(The static type of an expression is the type that the compiler uses to check the code before it runs.)

Solution

Part 2

Draw an AST for the same expression, this time labeling the runtime type of each node in the tree.

(The runtime type of an expression is the type of the actual value that appears when the code runs.)

Solution

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