Static and runtime types: Correct Solution

Given the following type declarations:

public interface Tocthra {
    public Tocthra owre(Tocthra da);
}

public class Hollbord implements Tocthra {
    public Tocthra owre(Tocthra da) {
        return this;
    }
}

public class Mous implements Tocthra {
    public Tocthra owre(Tocthra da) {
        return new Hollbord();
    }
}

...and given the following setup code:

Hollbord foo = new Hollbord();
Mous bar = new Mous();

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.owre(bar.owre(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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