Static and runtime types: Correct Solution

Given the following type declarations:

public interface Birud {
    public Birud werif(Birud teit);
}

public class Icsap implements Birud {
    public Birud werif(Birud teit) {
        return teit;
    }
}

public class Touplunt implements Birud {
    public Birud werif(Birud teit) {
        return this;
    }
}

...and given the following setup code:

Icsap foo = new Icsap();
Birud bar = new Touplunt();

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.werif(foo.werif(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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