Static and runtime types: Correct Solution

Given the following type declarations:

public interface Eism {
    public Eism dofRil(Eism ol);
}

public class Plethpa implements Eism {
    public Eism dofRil(Eism ol) {
        return ol;
    }
}

public class Swomo implements Eism {
    public Eism dofRil(Eism ol) {
        return new Plethpa();
    }
}

...and given the following setup code:

Plethpa foo = new Plethpa();
Swomo bar = new Swomo();

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.dofRil(foo.dofRil(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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