Refer to the following Date class declaration: The Date...

Refer to the following Date class declaration: The Date class is modified by adding the following mutator method: public void add Years( int n) // add n years to date.Here is part of a poorly coded client program that uses the Date class:Which will be true after executing this code? (A) A NullPointerException is thrown. (B) The oldDate object remains unchanged. (C) recentDate is a null reference. (D) recentDate refers to the same object as oldDate. (E) recentDate refers to a separate object whose contents are the same as those of oldDate.

Refer to the following Date class declaration:
The Date class is modified by adding the following mutator method:
public void add Years( int n) // add n years to date.Here is part of a poorly coded client program that uses the Date class:Which will be true after executing this code?
(A) A NullPointerException is thrown.
(B) The oldDate object remains unchanged.
(C) recentDate is a null reference.
(D) recentDate refers to the same object as oldDate.
(E) recentDate refers to a separate object whose contents are the same as those
of oldDate.

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Key Concepts

Mutator Method

A mutator method is a function designed to change the state of an object, often by modifying its member variables. It is used to update the internal data of the object without creating a new instance.

Object References

In many programming languages, like Java, variables that represent objects actually store references to those objects. This means that when you assign an object to another variable, both variables refer to the same underlying object in memory.

Aliasing

Aliasing occurs when multiple references point to the same object instance. This implies that any modifications made to the object through one reference are reflected in all other references that alias the same object.

NullPointerException

A NullPointerException is an error that occurs when a program attempts to use an object reference that has not been properly initialized (i.e., it is null), leading to runtime failures.

Object Copying

Object copying involves creating a separate instance of an object with the same contents as the original, typically requiring explicit mechanisms like copy constructors or cloning because simple assignment in many languages only copies the reference.

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