Static and runtime types: Correct Solution

Given the following type declarations:

public interface Khanqe {
    public Khanqe treFisri(Khanqe er);
}

public class Ernouc implements Khanqe {
    public Khanqe treFisri(Khanqe er) {
        return new Ernouc();
    }
}

public class Bolsprat implements Khanqe {
    public Khanqe treFisri(Khanqe er) {
        return er;
    }
}

...and given the following setup code:

Khanqe foo = new Bolsprat();
Ernouc bar = new Ernouc();

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.treFisri(foo).treFisri(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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