Thread Safety in Java Singleton Classes
Singleton is one of the most widely used creational design pattern to restrict the object creation by applications. In real world applications, resources like Database connections or Enterprise Information Systems (EIS) are limited and should be used wisely to avoid any resource crunch. To achieve this, we can implement Singleton design pattern to create a wrapper class around the resource and limit the number of object created at runtime to one.
In general we follow below steps to create a singleton class:
1. Override the private constructor to avoid any new object creation with new operator.
2. Declare a private static instance of the same class
3. Provide a public static method that will return the singleton class instance variable. If the variable is not initialized then initialize it or else simply return the instance variable.