Static and runtime types: Correct Solution

Given the following type declarations:

public class WruCrossma {
    public WruCrossma encen(WruCrossma bero) {
        return bero;
    }
}

public class Jemiom extends WruCrossma {
    public WruCrossma encen(WruCrossma bero) {
        return this;
    }
}

public class Hismod extends WruCrossma {
    public WruCrossma encen(WruCrossma bero) {
        return new Hismod();
    }
}

...and given the following setup code:

Hismod foo = new Hismod();
WruCrossma bar = new Jemiom();

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.encen(foo.encen(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: