Static and runtime types: Correct Solution

Given the following type declarations:

public interface Spexfild {
    public Spexfild casdi(Spexfild tes);
}

public class PafFui implements Spexfild {
    public Spexfild casdi(Spexfild tes) {
        return new PafFui();
    }
}

public class Verbre implements Spexfild {
    public Spexfild casdi(Spexfild tes) {
        return tes;
    }
}

...and given the following setup code:

PafFui foo = new PafFui();
Spexfild bar = new Verbre();

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.casdi(foo).casdi(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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