A. In the second statement below, which definition of toString is invoked? Selec

Question

A. In the second statement below, which definition of toString is invoked?

Select one:

a. The definition in X.

b. None of the choices, a compiler error is incurred.

c. The definition in Object.

d. The definition in Z.

B. In the second statement below, which definition of toString is invoked?

Select one:

a. The definition in Z.

b. The definition in Object.

c. None of the choices, a compiler error is incurred.

d. The definition in X.

C. In the second statement below, which definition of equals is invoked?

Select one:

a. The definition in Y.

b. The definition in Object.

c. None of the choices, a compiler error is incurred.

d. The definition in W.

D. In the second statement below, which definition of equals is invoked?

Select one:

a. The definition in Object.

b. The definition in W.

c. The definition in Y.

d. None of the choices, a compiler error is incurred.

E. In the second statement below, which definition of foo is invoked?

Select one:

a. None of the choices, a compiler error is incurred.

b. The definition in Z.

c. The definition in Y.

d. The definition in W.

F. In the second statement below, which definition of foo is invoked?

Select one:

a. None of the choices, a compiler error is incurred.

b. The definition in W.

c. The definition in Z.

d. The definition in Y.

Explanation / Answer

A. Ans(c) The definition in Object.

Explaination: Since the reference and object are of same type thus there should be no confusion. toString() of W will be invoked.

B. Ans(a) . The definition in Z.

Explaination: It is a concept of dynamic polymorphism in which an overridden method is invoked at run time, no matter what data type the reference is that was used in the source code at compile time. Its is the object whose method will be invoked not the reference. here the reference is of type W but object Z thus method of Z will be invoked.

C) Ans(b) The definition in Object.

Explaination: Since X does not overide equals method so equals method of W will be invoked.

D) Ans(c) The definition in Y.

Explaination: Since Z itself doesnot overide equals method so equals method of its immediate parent will be invoked.

E) Ans(d) The definition in W.

Explaination: method foo(int) of W will be invoked because foo() of Y doesnot have any parameter and there will be no method overriding.

F) Ans(a) None of the choices, a compiler error is incurred.

Explaination: Thie compiler will generate an error because method binding takes place at run time and compiler will look for method foo() in W at compile time because reference is of type W and W doesnot contain foo() but contains foo(int).

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