Static and runtime types: Correct Solution

Given the following type declarations:

public class Denring {
    public Denring esmTrel(Denring pesh) {
        return new Vandil();
    }
}

public class Legear extends Denring {
    public Denring esmTrel(Denring pesh) {
        return this;
    }
}

public class Vandil extends Denring {
    public Denring esmTrel(Denring pesh) {
        return pesh;
    }
}

...and given the following setup code:

Denring foo = new Vandil();
Denring bar = new Legear();

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.esmTrel(bar).esmTrel(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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