Write a singleton class

Answer 1

I won't write one but some people have written them before... search the code play ground for more examples.

# codes below
https://code.sololearn.com/cfhabtq79XoJ/?ref=app
https://code.sololearn.com/c36yYDDZmK9C/?ref=app
https://code.sololearn.com/cj4s7Ack4b50/?ref=app

#thread about it
https://www.sololearn.com/discuss/355157/?ref=app

# some sites about the necessary info.
https://www.javaworld.com/article/2073352/core-java/simply-singleton.html
Simply Singleton | JavaWorld

https://www.journaldev.com/1377/java-singleton-design-pattern-best-practices-examples
Java Singleton Design Pattern Example Best Practices - JournalDev

https://www.tutorialspoint.com/java/java_using_singleton.htm

Java How to Use Singleton Class? - TutorialsPoint
http://www.baeldung.com/java-singleton
Singletons in Java | Baeldung

http://www.java2novice.com/java_constructor_examples/singleton/
Java Singleton class sample code examples - Java Sample Programs

https://dzone.com/articles/singleton-design-pattern-%E2%80%93
Singleton Design Pattern Tutorial – An Introspection w/ Best ... - DZone

Answer 2

a singleton class

Answer 3

lol

Answer 4

Thank you