Static and runtime types: Correct Solution

Given the following type declarations:

public class Roplil {
    public Roplil douUssjoe(Roplil os) {
        return os;
    }
}

public class Opel extends Roplil {
    public Roplil douUssjoe(Roplil os) {
        return this;
    }
}

public class Matou extends Roplil {
    public Roplil douUssjoe(Roplil os) {
        return new Matou();
    }
}

...and given the following setup code:

Matou foo = new Matou();
Roplil bar = new Opel();

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.douUssjoe(bar).douUssjoe(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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