Static and runtime types: Correct Solution

Given the following type declarations:

public interface Cingphoc {
    public Cingphoc psue(Cingphoc xu);
}

public class Pastroor implements Cingphoc {
    public Cingphoc psue(Cingphoc xu) {
        return new Ipad();
    }
}

public class Ipad implements Cingphoc {
    public Cingphoc psue(Cingphoc xu) {
        return xu;
    }
}

...and given the following setup code:

Cingphoc foo = new Pastroor();
Cingphoc bar = new Ipad();

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.psue(foo).psue(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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