What is a singleton class and when do you use it?

Asked by Last Modified  

10 Answers

Learn Java

Follow 3
Answer

Please enter your answer

Vishal Deep

7+ year of corporate Experience in Manual & Automation(Java + Selenium) Testing in IT industry

Singleton class have a private constructor. while we can't create an object from outside of class, we can create an object only once.
Comments
Dislike Bookmark

2 Days Free Demo Classes

One reason that tends to come up over and over again on the internets is that of a "logging" class (which you mentioned). In this case, a Singleton can be used instead of a single instance of a class because a logging class usually needs to be used over and over again ad nauseam by every class in a project....
read more
One reason that tends to come up over and over again on the internets is that of a "logging" class (which you mentioned). In this case, a Singleton can be used instead of a single instance of a class because a logging class usually needs to be used over and over again ad nauseam by every class in a project. If every class uses this logging class, dependency injection becomes cumbersome. Logging is a specific example of an "acceptable" Singleton because it doesn't affect the execution of your code. Disable logging, code execution remains the same. Enable it, same same. Misko puts it in the following way in Root Cause of Singletons, "The information here flows one way: From your application into the logger. Even though loggers are global state, since no information flows from loggers into your application, loggers are acceptable." read less
Comments
Dislike Bookmark

Tutor

Singleton class has only one instance and is generally meant for shortened finish of a program
Comments
Dislike Bookmark

Big Data Expert

A class is called singleton when it limits the number of object creation for that class to be one. We can't have more than a single object of that class. Singleton class are employed extensively in concepts like networking and database connectivity.
Comments
Dislike Bookmark

Trainer

singleton is a design pattern that restricts the instantiation of a class to one object.
Comments
Dislike Bookmark

B.E. (IT)

One reason that tends to come up over and over again on the internets is that of a "logging" class (which you mentioned). In this case, a Singleton can be used instead of a single instance of a class because a logging class usually needs to be used over and over again ad nauseam by every class in a project....
read more
One reason that tends to come up over and over again on the internets is that of a "logging" class (which you mentioned). In this case, a Singleton can be used instead of a single instance of a class because a logging class usually needs to be used over and over again ad nauseam by every class in a project. If every class uses this logging class, dependency injection becomes cumbersome. Logging is a specific example of an "acceptable" Singleton because it doesn't affect the execution of your code. Disable logging, code execution remains the same. Enable it, same same. Misko puts it in the following way in Root Cause of Singletons, "The information here flows one way: From your application into the logger. Even though loggers are global state, since no information flows from loggers into your application, loggers are acceptable." Singleton candidate must satisfy three requirements: controls concurrent access to a shared resource. access to the resource will be requested from multiple, disparate parts of the system. there can be only one object. If your proposed Singleton has only one or two of these requirements, a redesign is almost always the correct option. For example, a printer spooler is unlikely to be called from more than one place (the Print menu), so you can use mutexes to solve the concurrent access problem. A simple logger is the most obvious example of a possibly-valid Singleton, but this can change with more complex logging schemes. read less
Comments
Dislike Bookmark

Java trainer , Data structure and algorithms

Singleton design pattern can be obtained by using following steps: 1.Private Constructor 2.Static Factory Method 3.Static Reference Object Creation As we are using a Static Reference Object Creation ,it is a "static" member and a static member can execute only one time and will create only one object. Creating...
read more
Singleton design pattern can be obtained by using following steps: 1.Private Constructor 2.Static Factory Method 3.Static Reference Object Creation As we are using a Static Reference Object Creation ,it is a "static" member and a static member can execute only one time and will create only one object. Creating only one Object for the entire class saves the memory space and which helps to not to degrade the performance, which is most important. Since we are able to create exactly one instance for one class ,it is called as Singleton class read less
Comments
Dislike Bookmark

Talent with Professional Experience

Singleton class is a class which has one instance
Comments
Dislike Bookmark

Trainer

A singleton should be used when managing access to a resource which is shared by the entire application, and it would be destructive to potentially have multiple instances of the same class
Comments
Dislike Bookmark

Trainer

A singleton class is one which has only one object of itself own which is a static object and outside the class we cant create another object as the constructor is private.
Comments
Dislike Bookmark

View 8 more Answers

Related Questions

What is an Exception in Java?
We can Say Exception is an event which terminates the normal execution of a program
Piyush
0 0
5
Is it possible to learn java at home without coaching in one month?
It all depends on you. If you are already aware of programming then it is definetly possible to learn java at home. But if learn through a tutor then you can learn easily.
Pritom
0 0
5
How to handle Circular dependency in Spring?
What I would like to do in this post is suggest 3 possible techniques for dealing with this problem. 1. Refactor your code This is probably the simplest and quickest way to fix this problem. Look at...
Saroj
Why we are using this keyword in Java?
to access current object
Kiran
0 0
9
What are the technologies to learn for a Java backend developer?
One of the most critical skills of a backend developer is a depth of knowledge in backend programming languages. This includes proficiency in PHP, Java, Python, Perl, Ruby, and Node JS.
Ankita
0 0
5

Now ask question in any of the 1000+ Categories, and get Answers from Tutors and Trainers on UrbanPro.com

Ask a Question

Related Lessons

2.1. Reverse a singly linked list.
class Node { int data; Node next; Node(int data) { this.data = data; this.next = null; }} public class LinkedList { Node head; public void reverse() { Node prev = null; Node curr = head; Node next =...

Vivek J.

0 0
0
Syntax and example of java
Java syntax: Class Display - - class definition { Void Display() { System.out.println('welcome to Java') ; } Public static void main(String arcs) { Display D=new Display() ;--object creation D. Display } }

Semalla Santosh Kumar

0 0
0
4 Things Every Tech Startup Needs to Know About The Coaching Industry
Knowledge on any subject is widely available to those who wish to learn. However, just gathering knowledge from other people doesn’t guarantee results in business. Results come from applying what...

Rajesh N V

3 0
1
Java : Compile-time Versus Runtime optimization
While designing and development, one should think in terms of compile-time and run-time.It helps in understanding language basics in a better way.Let's understand this with a question below : What...
S

Surinder Pal Singh

1 0
0
Most Important Java Interview Topics
Dear All, I am here to help on java interview preparation for fresher and experienced people, please get in touch with me for further details. All interview preparation will be with unique teaching style...

Rahul

1 0
0

Recommended Articles

Why Java is the Most Popular Programming Language

Designed in a flexible and user-friendly demeanor, Java is the most commonly used programming language for the creation of web applications and platform. It allows developers to “write once, run anywhere” (WORA). It is general-purpose, a high-level programming language developed by Sun Microsystem. Initially known as an...

Read full article >

Some Popular IT Courses in Current Market

In the domain of Information Technology, there is always a lot to learn and implement. However, some technologies have a relatively higher demand than the rest of the others. So here are some popular IT courses for the present and upcoming future: Cloud Computing Cloud Computing is a computing technique which is used...

Read full article >

Why Should You Learn Java !

Java is the most famous programming language till date. 20 years is a big time for any programming language to survive and gain strength. Java has been proved to be one of the most reliable programming languages for networked computers. source:techcentral.com Java was developed to pertain over the Internet. Over...

Read full article >

Java: An Object-Oriented Language

Java is the most commonly used popular programming language for the creation of web applications and platform today. Integrated Cloud Applications and Platform Services Oracle says, “Java developers worldwide has over 9 million and runs approximately 3 billion mobile phones”.  Right from its first implication as java 1.0...

Read full article >

Find Java Certification near you
Java Certification in Bangalore
Java Certification in Hyderabad
Java Certification in Pune
Java Certification in Chennai
Java Certification in Delhi
Java Certification in Mumbai
Java Certification in Kolkata
Java Certification in Noida
Java Certification in Gurgaon
Java Certification in Ghaziabad
Online Java Training

Looking for Java Training Classes?

Learn from the Best Tutors on UrbanPro

Are you a Tutor or Training Institute?

Join UrbanPro Today to find students near you