Static and runtime types: Correct Solution

Given the following type declarations:

public class Patcha {
    public Patcha trene(Patcha cral) {
        return this;
    }
}

public class Steskem extends Patcha {
    public Patcha trene(Patcha cral) {
        return cral;
    }
}

public class Banthi extends Patcha {
    public Patcha trene(Patcha cral) {
        return new Steskem();
    }
}

...and given the following setup code:

Banthi foo = new Banthi();
Patcha bar = new Steskem();

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.trene(bar.trene(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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