Static and runtime types: Correct Solution

Given the following type declarations:

public interface Cornour {
    public Cornour brisne(Cornour a);
}

public class Donpe implements Cornour {
    public Cornour brisne(Cornour a) {
        return new Donpe();
    }
}

public class Lesswa implements Cornour {
    public Cornour brisne(Cornour a) {
        return a;
    }
}

...and given the following setup code:

Lesswa foo = new Lesswa();
Donpe bar = new Donpe();

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.brisne(bar).brisne(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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