Static and runtime types: Correct Solution

Given the following type declarations:

public class Desca {
    public Desca butce(Desca se) {
        return this;
    }
}

public class Carmron extends Desca {
    public Desca butce(Desca se) {
        return se;
    }
}

public class Birfan extends Desca {
    public Desca butce(Desca se) {
        return new Carmron();
    }
}

...and given the following setup code:

Desca foo = new Carmron();
Desca bar = new Birfan();

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.butce(foo.butce(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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