19 The following Java code presents three class definitions and four object inst

Question

19 The following Java code presents three class definitions and four object instantiations (below the line). What is displayed by the four printin statements at the end? public class Vertebrate public String whoAreYou0 ( return "Vertebrate",) public class Mammal extends Vertebrate public String whoAreYou0 ( return "Mammal", ) public class Canine extends Mammal public String whoAreYou0 ( return "Canine" ) Vertebrate v0 = new Vertebrate(); Vertebrate v1- new Mammal); Mammal m - new Canine); Vertebrate v2 new Canine(); System.out.printin (v0.whoAreYou)) System.out.println (v1.whoAreYou)), System.out.println(m.whoAreYou) System.out.println(v2.whoAreYou)); O Vertebrate, Vertebrate, Mammal, Vertebrate O Vertebrate, Mammal, Canine, Vertebrate O Vertebrate, Mammal, Canine, Canine

Explanation / Answer

Answer : (a)

v0 executes the whoAreYou() function in Vertebrate class. So, it prints

Vertebrate

A reference of super class can also refer to the object of the base class, but it can only access the functions in the super class. In case of overridden function, the function in the super class is executed.

So, v1 points the object of type Mammal, but the function is called in the Vertebrate class. So, it prints

Vertebrate

Also, m points the object of type Canine, but the function is called in the Mammal class. So, it prints

Mammal

So, v2 points the object of type Vertebrate, but the function is called in the Vertebrate class. So, it prints

Vertebrate

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