Static and runtime types: Correct Solution

Given the following type declarations:

public interface Pamtia {
    public Pamtia dissar(Pamtia sce);
}

public class Scetec implements Pamtia {
    public Pamtia dissar(Pamtia sce) {
        return sce;
    }
}

public class Grack implements Pamtia {
    public Pamtia dissar(Pamtia sce) {
        return new Scetec();
    }
}

...and given the following setup code:

Grack foo = new Grack();
Pamtia bar = new Scetec();

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.dissar(foo.dissar(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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