Static and runtime types: Correct Solution

Given the following type declarations:

public interface Coasspa {
    public Coasspa brang(Coasspa di);
}

public class Eadgi implements Coasspa {
    public Coasspa brang(Coasspa di) {
        return new Glall();
    }
}

public class Glall implements Coasspa {
    public Coasspa brang(Coasspa di) {
        return this;
    }
}

...and given the following setup code:

Eadgi foo = new Eadgi();
Glall bar = new Glall();

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.brang(bar).brang(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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