Static and runtime types: Correct Solution

Given the following type declarations:

public class Crewo {
    public Crewo duee(Crewo mi) {
        return this;
    }
}

public class Silroc extends Crewo {
    public Crewo duee(Crewo mi) {
        return mi;
    }
}

public class Odru extends Crewo {
    public Crewo duee(Crewo mi) {
        return new Odru();
    }
}

...and given the following setup code:

Crewo foo = new Silroc();
Crewo bar = new Odru();

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.duee(bar.duee(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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