Static and runtime types: Correct Solution

Given the following type declarations:

public interface Tinggre {
    public Tinggre ogra(Tinggre oin);
}

public class Pelfasm implements Tinggre {
    public Tinggre ogra(Tinggre oin) {
        return this;
    }
}

public class Peuss implements Tinggre {
    public Tinggre ogra(Tinggre oin) {
        return new Pelfasm();
    }
}

...and given the following setup code:

Pelfasm foo = new Pelfasm();
Tinggre bar = new Peuss();

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.ogra(bar.ogra(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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