{"id":1209,"date":"2022-08-07T00:12:36","date_gmt":"2023-05-19T06:37:44","guid":{"rendered":"https:\/\/www.silicloud.com\/blog\/uncategorized\/ensuring-thread-safety-in-java-singleton-classes\/"},"modified":"2024-03-10T15:02:57","modified_gmt":"2024-03-10T15:02:57","slug":"ensuring-thread-safety-in-java-singleton-classes","status":"publish","type":"post","link":"https:\/\/www.silicloud.com\/blog\/ensuring-thread-safety-in-java-singleton-classes\/","title":{"rendered":"Ensuring thread safety in Java Singleton Classes"},"content":{"rendered":"

The Singleton design pattern is extensively employed to control object creation in applications. Ensuring thread safety for the singleton class is crucial when used in a multi-threaded environment. In real-world scenarios, it is essential to use limited resources like Database connections or Enterprise Information Systems (EIS) wisely in order to prevent any shortage. This can be accomplished by implementing a Singleton design pattern, which involves creating a wrapper class for the resource and restricting the number of objects created to just one during runtime.<\/p>\n

Java’s Thread<\/a> Safe Singleton<\/h2>\n
\"thread<\/div>\n
    To prevent the creation of new objects using the new operator, implement a private constructor. Define a private static instance of the class and offer a public static method that returns the instance variable of the singleton class. If the variable is not yet initialized, initialize it; otherwise, return the instance variable.<\/ol>\n

    After following the aforementioned steps, I have successfully developed a singleton class known as ASingleton.java.<\/p>\n

    package com.scdev.designpatterns;\r\n\r\npublic class ASingleton {\r\n\r\n\tprivate static ASingleton instance = null;\r\n\r\n\tprivate ASingleton() {\r\n\t}\r\n\r\n\tpublic static ASingleton getInstance() {\r\n\t\tif (instance == null) {\r\n\t\t\tinstance = new ASingleton();\r\n\t\t}\r\n\t\treturn instance;\r\n\t}\r\n\r\n}\r\n<\/code><\/pre>\n
    The getInstance() method in the provided code is not thread-safe, meaning that multiple threads can access it concurrently. When the instance variable is not yet initialized, the first few threads can enter the if loop simultaneously and generate multiple instances, which would undermine the implementation of our singleton.<\/p>\n
    What is the approach to ensure thread-safety in a Singleton Class?<\/h2>\n
    We can accomplish thread safety in three different ways.<\/p>\n
      One advantage is that the instance variable is created during the loading of the class.<\/ol>\n