Sun Certified Java Programmer (SCJP) Questions

Which is the most suitable Java collection class for storing various companies and their stock prices? It is required that the class should support synchronization inherently.

Choices:

• A. Hashtable


• B. HashMap


• C. LinkedHashMap


• D. HashSet


• E. TreeMap

Correct choice:

• A

Explanation:

To store the company names and their corresponding stock prices, a Map implementation would be appropriate because it stores key-value pairs. HashSet is not the correct answer because it does not implement the Map interface. Hashtable, HashMap, TreeMap, and LinkedHashMap are the classes that implement the Map interface. Among these, only the Hashtable class is inherently synchronized.

We learned about the different types of collections like Lists, Sets, and Maps. It is important to understand the behavior of each of them and the situation in which they are preferred or required. We also saw the significance of the equals() and hashCode() methods. You should know the appropriate ways to implement these methods.

Summary

This wraps up the SCJP tutorial. It would be advisable to test each new concept you learned with the help of small practice examples. This will help foster your understanding of the material presented in this tutorial.

The most difficult questions in the exam center around threads and garbage collection. Pay extra attention to these chapters. Remember that the garbage collector and thread scheduler implementations are platform specific.

It is not enough if you just memorize the syntax and APIs that are part of the exam. It is very important to acquire a deep understanding of the core concepts covered in the exam objectives.

Regardless of your reasons for going after certification -- whether you want the professional advantage or the personal challenge (or whether getting certified is a job requirement) -- your approach to the task will determine the success of its outcome. Good preparation, attention to details, and a positive attitude are essential if you want to pass the SCJP exam.

I hope this tutorial is helpful in preparing you for your exam, and I wish you the best of luck.