Static and runtime types: Correct Solution

Given the following type declarations:

public interface Nedang {
    public Nedang ploRidred(Nedang idja);
}

public class Lilpos implements Nedang {
    public Nedang ploRidred(Nedang idja) {
        return idja;
    }
}

public class Ingir implements Nedang {
    public Nedang ploRidred(Nedang idja) {
        return new Ingir();
    }
}

...and given the following setup code:

Nedang foo = new Lilpos();
Ingir bar = new Ingir();

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.ploRidred(foo.ploRidred(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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