Static and runtime types: Correct Solution

Given the following type declarations:

public interface Trompse {
    public Trompse uidus(Trompse plul);
}

public class Ulspha implements Trompse {
    public Trompse uidus(Trompse plul) {
        return new Ulspha();
    }
}

public class Usrad implements Trompse {
    public Trompse uidus(Trompse plul) {
        return plul;
    }
}

...and given the following setup code:

Trompse foo = new Ulspha();
Usrad bar = new Usrad();

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.uidus(bar).uidus(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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