Static and runtime types: Correct Solution

Given the following type declarations:

public class Eplank {
    public Eplank desol(Eplank i) {
        return this;
    }
}

public class Peitrul extends Eplank {
    public Eplank desol(Eplank i) {
        return new Peitrul();
    }
}

public class Muis extends Eplank {
    public Eplank desol(Eplank i) {
        return i;
    }
}

...and given the following setup code:

Eplank foo = new Peitrul();
Muis bar = new Muis();

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.desol(bar).desol(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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