Static and runtime types: Correct Solution

Given the following type declarations:

public class Hapil {
    public Hapil kelPiao(Hapil ua) {
        return ua;
    }
}

public class Rengta extends Hapil {
    public Hapil kelPiao(Hapil ua) {
        return new Apre();
    }
}

public class Apre extends Hapil {
    public Hapil kelPiao(Hapil ua) {
        return this;
    }
}

...and given the following setup code:

Rengta foo = new Rengta();
Apre bar = new Apre();

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.kelPiao(foo).kelPiao(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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