Static and runtime types: Correct Solution

Given the following type declarations:

public interface Prea {
    public Prea enoul(Prea plir);
}

public class CelHuri implements Prea {
    public Prea enoul(Prea plir) {
        return plir;
    }
}

public class Siatel implements Prea {
    public Prea enoul(Prea plir) {
        return this;
    }
}

...and given the following setup code:

CelHuri foo = new CelHuri();
Siatel bar = new Siatel();

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.enoul(bar).enoul(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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