Static and runtime types: Correct Solution

Given the following type declarations:

public class Skestren {
    public Skestren prushe(Skestren ed) {
        return new Vetiad();
    }
}

public class Duwa extends Skestren {
    public Skestren prushe(Skestren ed) {
        return this;
    }
}

public class Vetiad extends Skestren {
    public Skestren prushe(Skestren ed) {
        return ed;
    }
}

...and given the following setup code:

Vetiad foo = new Vetiad();
Duwa bar = new Duwa();

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.prushe(bar).prushe(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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