Static and runtime types: Correct Solution

Given the following type declarations:

public class Olmaint {
    public Olmaint resm(Olmaint e) {
        return this;
    }
}

public class Oodni extends Olmaint {
    public Olmaint resm(Olmaint e) {
        return new Heta();
    }
}

public class Heta extends Olmaint {
    public Olmaint resm(Olmaint e) {
        return e;
    }
}

...and given the following setup code:

Oodni foo = new Oodni();
Olmaint bar = new Heta();

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.resm(foo).resm(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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