In JavaBeans listener naming conventions, how many of the following method names follow the standard listener pattern: addListener, addMouseListener, deleteMouseListener, removeMouseListener, registerMouseListener?

Introduction / Context:
JavaBeans define naming conventions for many components, including event listener registration methods. These conventions help frameworks and tools discover listeners through reflection. A common interview question is to count how many given method names follow the listener naming rules, which are based on add and remove prefixes plus the listener type name.

Given Data / Assumptions:

• We are given five method names: addListener, addMouseListener, deleteMouseListener, removeMouseListener, registerMouseListener.
• JavaBeans listener naming rules specify certain prefixes.
• Listener types typically end with the suffix Listener, such as MouseListener.
• The question is asking how many names follow the convention, not which specific names are valid methods in a particular API.

Concept / Approach:
In JavaBeans, the standard naming pattern for listener registration methods is addXListener and removeXListener, where X is the listener type name such as Mouse. The method names should begin with add or remove, followed by the exact listener interface name. Generic names like addListener without a specific listener type do not follow the full convention. Names with other verbs such as delete or register also do not follow the formal JavaBeans listener naming pattern, even if they might be understandable to humans.

Step-by-Step Solution:
Step 1: Recall the JavaBeans convention: listener registration methods use addXListener and removeXListener patterns. Step 2: Examine addListener: it uses add but lacks a specific listener type name, so it does not fully match addXListener. Step 3: Examine addMouseListener: it matches add + MouseListener exactly, so it follows the convention. Step 4: Examine deleteMouseListener: it uses delete instead of add or remove, so it does not follow the convention. Step 5: Examine removeMouseListener: it matches remove + MouseListener, so it follows the convention. Examine registerMouseListener: it uses register instead of add or remove, so it does not match. Therefore, exactly two names follow the listener naming rules.

Verification / Alternative check:
Looking at common Java APIs confirms this pattern. For example, many GUI frameworks, including AWT and Swing, provide methods like addMouseListener and removeMouseListener, but not deleteMouseListener or registerMouseListener. Tools that rely on JavaBeans conventions scan for methods starting with add and remove followed by a listener type name, which matches addMouseListener and removeMouseListener but not the other variants presented in the question.

Why Other Options Are Wrong:
Option A (1) is incorrect because there are at least two method names that match the addXListener/removeXListener pattern. Option C (3) and Option D (4) incorrectly count extra methods that do not start with add or remove plus the full listener type name. Specifically, addListener lacks the type, and deleteMouseListener and registerMouseListener use nonstandard verbs. Only addMouseListener and removeMouseListener follow the exact listener naming rules.

Common Pitfalls:
Developers sometimes design APIs with verbs like register, subscribe, or delete, which may be readable but do not align with JavaBeans naming conventions, reducing tool support. Another mistake is using generic names like addListener without specifying the listener type, which can be ambiguous in systems with multiple listener interfaces. Following the standard addXListener and removeXListener pattern helps tools and other developers understand and integrate with your listener based APIs.

Final Answer:
Exactly 2 of the given method names follow the JavaBean listener naming rules: addMouseListener and removeMouseListener.