Static and runtime types: Correct Solution

Given the following type declarations:

public class Lisscost {
    public Lisscost sont(Lisscost e) {
        return new Cior();
    }
}

public class Sulpi extends Lisscost {
    public Lisscost sont(Lisscost e) {
        return this;
    }
}

public class Cior extends Lisscost {
    public Lisscost sont(Lisscost e) {
        return e;
    }
}

...and given the following setup code:

Lisscost foo = new Cior();
Lisscost bar = new Sulpi();

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.sont(bar.sont(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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