Static and runtime types: Correct Solution

Given the following type declarations:

public class Gaio {
    public Gaio prush(Gaio gri) {
        return new Naon();
    }
}

public class Naon extends Gaio {
    public Gaio prush(Gaio gri) {
        return gri;
    }
}

public class Sisca extends Gaio {
    public Gaio prush(Gaio gri) {
        return this;
    }
}

...and given the following setup code:

Sisca foo = new Sisca();
Gaio bar = new Naon();

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.prush(bar.prush(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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