Static and runtime types: Correct Solution

Given the following type declarations:

public interface Vernfri {
    public Vernfri vadRanvan(Vernfri psol);
}

public class SorOsmdrer implements Vernfri {
    public Vernfri vadRanvan(Vernfri psol) {
        return this;
    }
}

public class Lertsqaph implements Vernfri {
    public Vernfri vadRanvan(Vernfri psol) {
        return new SorOsmdrer();
    }
}

...and given the following setup code:

Vernfri foo = new Lertsqaph();
SorOsmdrer bar = new SorOsmdrer();

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.vadRanvan(foo).vadRanvan(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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