Static and runtime types: Correct Solution

Given the following type declarations:

public class Varpreiss {
    public Varpreiss bafot(Varpreiss e) {
        return this;
    }
}

public class Selin extends Varpreiss {
    public Varpreiss bafot(Varpreiss e) {
        return new Emost();
    }
}

public class Emost extends Varpreiss {
    public Varpreiss bafot(Varpreiss e) {
        return e;
    }
}

...and given the following setup code:

Varpreiss foo = new Emost();
Selin bar = new Selin();

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.bafot(foo).bafot(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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