Static and runtime types: Correct Solution

Given the following type declarations:

public interface Betren {
    public Betren sluThi(Betren apom);
}

public class Trou implements Betren {
    public Betren sluThi(Betren apom) {
        return this;
    }
}

public class Aleaer implements Betren {
    public Betren sluThi(Betren apom) {
        return new Aleaer();
    }
}

...and given the following setup code:

Trou foo = new Trou();
Betren bar = new Aleaer();

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.sluThi(bar.sluThi(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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