Other Ways of Singleton in Java [duplicate]

Answer 1

There are 3 ways to create a singleton in java.

1. eager initialization singleton

   public class Test {
       private static final Test TEST = new Test();
   
       private Test() {
       }
   
       public static Test getTest() {
           return TEST;
       }
   }
   

2. lazy initialization singleton (thread safe)

   public class Test {
       private static volatile Test test;
       private Test(){}
       public static Test getTest() {
           if(test == null) {
               synchronized(Test.class) {
                   if(test == null){test = new Test();}
               }
           }
           return test;
       }
   }
   

3. Bill Pugh Singleton with Holder Pattern (Preferably the best one)

   public class Test {
       private Test(){}
   
       private static class TestHolder {
           private static final Test TEST = new Test();
       }
   
       public static Test getInstance() {
           return TestHolder.TEST;
       }
   }