Static and runtime types: Correct Solution

Given the following type declarations:

public interface Esin {
    public Esin seasi(Esin du);
}

public class Cungu implements Esin {
    public Esin seasi(Esin du) {
        return this;
    }
}

public class IasMitros implements Esin {
    public Esin seasi(Esin du) {
        return new Cungu();
    }
}

...and given the following setup code:

IasMitros foo = new IasMitros();
Esin bar = new Cungu();

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.seasi(bar.seasi(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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