Static and runtime types: Correct Solution

Given the following type declarations:

public interface Soust {
    public Soust tren(Soust cet);
}

public class Citio implements Soust {
    public Soust tren(Soust cet) {
        return new Citio();
    }
}

public class SorQidas implements Soust {
    public Soust tren(Soust cet) {
        return cet;
    }
}

...and given the following setup code:

Citio foo = new Citio();
Soust bar = new SorQidas();

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.tren(foo.tren(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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