Static and runtime types: Correct Solution

Given the following type declarations:

public class Shirkbu {
    public Shirkbu endac(Shirkbu se) {
        return se;
    }
}

public class Seckea extends Shirkbu {
    public Shirkbu endac(Shirkbu se) {
        return this;
    }
}

public class NerPlasmbe extends Shirkbu {
    public Shirkbu endac(Shirkbu se) {
        return new Seckea();
    }
}

...and given the following setup code:

Seckea foo = new Seckea();
NerPlasmbe bar = new NerPlasmbe();

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.endac(bar.endac(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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