CODEWITHSUNDEEP
javasingleton
sahana
sahana

Reputation: 43

Singleton design pattern example please

I would like to know an example for singleton pattern like 5 threads trying to access a single text file.At a time only one should be able to read that and that in turn creates a file displaying date, thread name, contents.

Textfile- source

 A B C D





Text file - details of the threads and contents

  Date & Time    Thread name   Contents 
  mar 25 10.02         a        A B C D
  mar 25 10.05         b        A B C D

Thanks

Upvotes: 0

Views: 541

Answers (1)

Mik378
Mik378

Reputation: 22171

I disagree with @Peter Mensik.

Indeed, in a multithreaded environnement, the double-check locking solution is broken. http://www.cs.umd.edu/~pugh/java/memoryModel/DoubleCheckedLocking.html

The solution (and best practice) is to use the initialization-on-demand pattern :

example at the bottom of this page.

http://best-practice-software-engineering.ifs.tuwien.ac.at/patterns/singleton.html

This solution is useful when using JDK 1.4 and older.

In JDK 1.5, you can use enum also.

For better understanding, you can read this excellent article :

http://www.ibm.com/developerworks/java/library/j-dcl/index.html

Upvotes: 1

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