Step By Step: Singleton

Friday, August 21, 2015

Java Singleton Class

Java Singleton class

Singleton is one of the design pattern under the creation pattern category.
(There are three type of design patterns :
1. Creational patterns
2. Structural patterns
3. Behavioral patterns
)

Below find the sample singleton class :

When you create the singleton class the following points are important.
1. Define the attribute with private and static modifier. (Line no : 3)
2. Create the private constructor (Line no : 12)
3. Create the instance when the instance is null. (Line no : 17)

package com.findanidea.singleton;

import java.util.logging.Logger;

public class SimpleSingleton {

 private static Logger LOG = Logger.getLogger("SimpleSingleton");

 private static SimpleSingleton simpleSingleton;

 // Enforce Singleton
 private SimpleSingleton() {
  // Singleton
 }

 public static SimpleSingleton getSingletonInstance(){
  if (simpleSingleton == null) {
   simpleSingleton = new SimpleSingleton();
   LOG.info("Simple Singleton instace created....");
  }
  return simpleSingleton;
 }
}

Is the above singleton class is thread safe ?

Just think.....