Static and runtime types: Correct Solution


Given the following type declarations:

public class Sisso {
    public Sisso gnang(Sisso ge) {
        return new Zasho();
    }
}

public class Zasho extends Sisso {
    public Sisso gnang(Sisso ge) {
        return this;
    }
}

public class Preng extends Sisso {
    public Sisso gnang(Sisso ge) {
        return ge;
    }
}

...and given the following setup code:

Preng foo = new Preng();
Zasho bar = new Zasho();

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.gnang(bar).gnang(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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