Static and runtime types: Correct Solution

Given the following type declarations:

public class Buma {
    public Buma phle(Buma swoi) {
        return this;
    }
}

public class Samaen extends Buma {
    public Buma phle(Buma swoi) {
        return new Samaen();
    }
}

public class Nonest extends Buma {
    public Buma phle(Buma swoi) {
        return swoi;
    }
}

...and given the following setup code:

Buma foo = new Samaen();
Nonest bar = new Nonest();

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.phle(bar).phle(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

Related puzzles: