Static and runtime types: Correct Solution

Given the following type declarations:

public class Popre {
    public Popre breusm(Popre be) {
        return be;
    }
}

public class Tarfi extends Popre {
    public Popre breusm(Popre be) {
        return this;
    }
}

public class Midpoc extends Popre {
    public Popre breusm(Popre be) {
        return new Midpoc();
    }
}

...and given the following setup code:

Popre foo = new Tarfi();
Popre bar = new Midpoc();

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.breusm(foo.breusm(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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