Static and runtime types: Correct Solution

Given the following type declarations:

public class SkaMip {
    public SkaMip nirat(SkaMip sua) {
        return sua;
    }
}

public class TesSimed extends SkaMip {
    public SkaMip nirat(SkaMip sua) {
        return new Deidsa();
    }
}

public class Deidsa extends SkaMip {
    public SkaMip nirat(SkaMip sua) {
        return this;
    }
}

...and given the following setup code:

Deidsa foo = new Deidsa();
TesSimed bar = new TesSimed();

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.nirat(foo.nirat(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: