Static and runtime types: Correct Solution

Given the following type declarations:

public interface Zufte {
    public Zufte nibrus(Zufte iss);
}

public class Pledept implements Zufte {
    public Zufte nibrus(Zufte iss) {
        return this;
    }
}

public class Storwo implements Zufte {
    public Zufte nibrus(Zufte iss) {
        return new Storwo();
    }
}

...and given the following setup code:

Pledept foo = new Pledept();
Storwo bar = new Storwo();

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.nibrus(foo).nibrus(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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