Static and runtime types: Correct Solution

Given the following type declarations:

public class CuaOrds {
    public CuaOrds uhal(CuaOrds scia) {
        return this;
    }
}

public class Ostspec extends CuaOrds {
    public CuaOrds uhal(CuaOrds scia) {
        return new Ostspec();
    }
}

public class Raltin extends CuaOrds {
    public CuaOrds uhal(CuaOrds scia) {
        return scia;
    }
}

...and given the following setup code:

Raltin foo = new Raltin();
CuaOrds bar = new Ostspec();

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.uhal(foo.uhal(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

Related puzzles: