Introduction
Amdocs is a MNC (Multi National Company). It was founded by Boaz Dotan and Morris Kahn. Amdocs was founded in 1982 in Israel. The company was headquartered in Chesterfield, Missouri. Amdocs provides software and services to companies working in digital enterprise, media, communications, etc. In this article, we will discuss Amdocs java interview questions. So, let's have a look at what Java is.

Java is a programming language and platform that is quite popular and widely utilized. A platform is a software development and execution environment. Java is a quick, dependable, and secure language. Java is a high-level, object-oriented programming language. It was first introduced in 1995 by Sun Microsystems. Java runs on various platforms, including Windows, UNIX, Mac OS, etc. Java creates mobile/web/desktop apps, games, and more.
To become proficient and perform well in interviews, one must first master the foundations of the language. It includes learning how to answer the company's interview questions.
Let's study collections of questions on one of the widely used programming languages. Let’s discuss the most common Amdocs Java interview questions.
Click on the following link to read further: Java OOPs Interview Questions
Amdocs Java Developer Interview Questions for Freshers
Let’s start the discussion. So, here are some Amdocs Java developer Interview questions.
1. Explain the thread life cycle in Java.
Ans: The thread cycle in Java consists of 5 states. These are:
- New - It is also known as the born thread. It is the beginning of the thread life cycle. A new thread is created in this state. A thread stays in this state until it is started.
- Active - This state is also known as a runnable state. A thread that is about to run is sent to an active state. The thread scheduler decides the running time of the thread present here.
- Waiting/Blocked - This state is achieved when the thread is temporarily inactive.
- Timed Waiting - In this state, the thread moves to the waiting state for a specified time.
- Terminated - A thread when to this state after the task is completed. This state can also occur because of some error.
2. What is the final keyword refers in Java?
Ans: The final keyword is used to make java elements non-changeable. These elements can be a class, attribute, interface, or method. This final keyword is a modifier in Java. The element declared with the final keyword always stores same value.
3. What is a collection framework in Java?
Ans: The Collection framework in Java provides a framework for storing and managing a collection of objects. It gives developers access to prepackaged data structures and data manipulation algorithms.
The following are part of the collection framework:
i) Interfaces
ii) Classes,
iii) Algorithms
These classes and interfaces support various operations such as searching, sorting, inserting, manipulating, and deleting, making data manipulation extremely simple and quick.
4. How is polymorphism implemented in Java?
Ans: The word Polymorphism is a combination of two words. 'Poly' means many, and 'Morphism' means forms.
In Java, Polymorphism is categorized as -
- Compile time Polymorphism: This is achieved by method overloading. This means multiple methods have the same name but different parameters.
- Run time polymorphism - This is achieved by method overriding. This means having the same methods in both child and parent classes.
5. What is wrapper class?
Ans: Wrapper class in Java is used for wrapping primitive data types in objects. This helps in using collection frameworks, as they store only objects. Also, objects are helpful for synchronization in multithreading. The classes of Java.util package only handles objects. So, the wrapper class makes it handy to use Java.util package. The wrapper classes of primitive classes are -
Primitive classes |
Wrapper classes |
int |
Integer |
char |
Character |
short |
Short |
long |
Long |
float |
Float |
double |
Double |
byte |
Byte |
boolean |
Boolean |
6. What is a garbage collector in Java?
Ans: JVM(Java Virtual Machine) has a feature known as a garbage collector(GC). It automatically makes the unused memory reusable. The garbage collector removes the objects that are unreferenced from heap memory. It is based on the 'Stop-the-World process'. In this process, JVM stops the whole application for a specific duration and un GC.
Along with advantages, GC can also affect the program's performance. It consumes more CPU resources to check free memory slots. Hence garbage collectors make our application slow. To measure the effect due to GC, we should keep our eyes on a few aspects -
- The number of occurrences of garbage collection.
- Duration for which garbage collector is running.
- The measure of resources used by garage collectors.
- Track if the garbage collection done is minor or complete.
- Percentage of time spent in garbage collection.
-
The type of memory used. It can be heap or non-heap memory.
7. Why is Java known as platform independent language?
Ans: Java uses a virtual machine known as Java virtual machine(JVM). When we compile our java code, this virtual machine converts it into byte code, as these byte codes can run on any platform. And Java uses these bytecode (.class) files to generate outputs. This functionality makes Java a platform-independent language.
8. What is the difference between the TRUNCATE and DELETE commands?
Ans: DELETE is a command of Data manipulation language . While TRUNCATE is a command of the Data Definition Language. The differences between both are -
TRUNCATE |
DELETE |
This command is used when we have to delete all the rows in the table. | When we have to delta a specified number of rows, then DELETE is used. |
The TRUNCATE command is faster. | The DELETE command is slower. |
Transaction space requirement is less. | Transaction space requirement is more. |
This command deallocates the data to remove all the rows. | This command removes one row at a time. Adds the record to the log table. |
9. Explain the thread pool.
Ans: In java, thread pool refers to a group of threads that can be reused. The size of a thread pool is fixed. The working is like a loop; threads are pulled from the pool. These threads are given to service providers. After completing the job given by the service provider, they are sent back to the thread pool. The thread pools help in saving a lot of time by making threads reusable. Also, thread pools are associated with some risks. These are -
-
Deadlock is a condition in which many threads are waiting for another process. This occurs when each process is either waiting or holding some resource for a more extended time.
-
Leakage - The risk of a thread being lost. This risk occurs when a thread is pulled out from the pool but not returned.
-
Resource waiting time - This risk occurs when the thread pool size is enormous. In this, a significant portion of time is wasted, and the resources must wait longer.
10. Explain how Java supports linked lists.
Ans: Java supports two forms of linked lists:
-
A singly linked list is a form of data structure. Each node in a single linked list retains that node's contents and a reference to the next node in the List. There is no reference or pointer to the previous node stored.
- The Doubly Linked List are a form of a linked list that allows traversal in both directions across the data items. This is made possible by each node having two links, one connecting to the next node and the other connecting to the previous node.
11. What are the differences between an overloading and an overriding
Ans: Iterator traverses the elements only forward, whereas ListIterator traverses the elements both forward and backward.
Overloading |
Overriding |
Overloading is done within the same class. | Overriding requires two classes, i.e., a parent class and one child class. |
There is no need of Inheritance in overloading. | The concept of Inheritance is must for implementing overriding. |
The type or number of parameters must be different for each method. | The type or number of parameters must be the same. |
The return type may be the same or not. | The return type must be the same. |
We can also change access and non-access modifiers. | Access modifiers may be the same or increase. Non-access modifiers are only final and static. |
You can also checkout Java List Iterator here
12. What are the differences between a HashSet and a TreeSet?
Ans: Both the HashSet and TreeSet implement the Set interface. The distinctions between the two are listed below-
- TreeSet maintains ascending order, whereas HashSet does not.
- TreeSet is implemented by a Tree structure, whereas a hash table supports HashSet.
- HashSet outperforms TreeSet. In performance, HashSet is better.
- TreeSet is supported by TreeMap, whereas HashMap supports HashSet.