Static and runtime types: Correct Solution

Given the following type declarations:

public interface Foosna {
    public Foosna iacu(Foosna uen);
}

public class Cesi implements Foosna {
    public Foosna iacu(Foosna uen) {
        return uen;
    }
}

public class Podtrue implements Foosna {
    public Foosna iacu(Foosna uen) {
        return this;
    }
}

...and given the following setup code:

Foosna foo = new Podtrue();
Cesi bar = new Cesi();

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.iacu(foo).iacu(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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