java singleton example

pattern can undoubtedly improve the performance of the system.(3) Allow a variable number of instances. Based on the singleton pattern, we can extend the method to obtain the specified number of object instances by using a similar approach to single-instance control, which saves system resources and solves the problem that single-instance objects share too much lossy performance.2. Main disadvantagesThe main disadvantages of the

The Java singleton pattern implements the attribute of only one instance of a class.Implementation mode: A hungry man type is very simple not elaborated. Below is a description of the lazy type. Constructor privatization The static method obtains the instance, the method inside double-check-locking checks. Synchronization methods are not recommended. public class

method to get instance directly and throws an error when instance is called. Volatile can prevent reordering.Four, through the inner class to implement the Singleton Public classsingleton{Private Static classsingletonholder{Private StaticSingleton instance =NewSingleton (); } PrivateSingleton () {}; Private Static volatileSingleton instance =NULL; Public StaticSingleton getinstance () {returnsingletonholder.instance; }}The instance of

instantiations of the class are given the same object, and the class can be instantiated at the global scope. For the moment, we don't care about its implementation, but first of all, what is the point of doing so? The point is that it ensures uniqueness and, to a certain extent, is a resource-saving function. For example, we use the same QQ account on the same computer to log on is a failure, because you do not need two exactly the same chat tool, t

In Java, the singleton pattern is a common design pattern, and the singleton pattern is divided into three kinds: lazy type single case, a hungry man type single case, registration type single case three kinds.There are a few features of the Singleton model:1, the Singleton

Java design mode-singleton mode and java Design Mode From the beginning of spring festival! I'm so drunk that I care about mountains and rivers! Every day, I am opening a new blog with two irrelevant poems! Small editors are the best in the field of code literature, and the best in the field of literature !! In any case, the first blog was born like this. It w

Singletonfour () {2021}2223public static Singletonfour getinstance () {return instance;30}31+}Seeing this method, the world has become more and more pure. Because of the Java mechanism, static member variables are initialized only once when the class is loaded, and class loading is thread-safe. So the single example implemented by this method is thread-safe. But this method sacrifices the lazy character. T

I can't make sure that the Singleton class can be actively used in other places to be loaded, It is obviously inappropriate to instantiate instance at this time. This time, this way is quite reasonable compared to the A Hungry man mode. PackageSingleton; Public classSingleton6 {Private Static classSingletonholder {Private Static FinalSingleton6 INSTANCE =NewSingleton6 (); } PrivateSingleton6 () {} Public Static FinalSingleton6 getinstance () {retu

//Student S1 = new Student ();5 //Student s2 = new Student ();6 //System.out.println (S1 = = s2);//false, the address value is not the same, proving to be 2 different objects7 8 9 //The following is a direct change to the value of the object s, in order to avoid such a situation, so in the student class, the object is added privateTen //student.s = null; One A //How do you get the object through a single

variable (uninitialized, does not use the final keyword, and volatile guarantees the visibility of the instance variable when multi-threaded access is avoided, and is called by another thread when the other variable property is not assigned when instance initialized) - Private Static volatileSingletontest instance; the - //defines a common static method that returns an instance of the type - Public Staticsingletontest getistance () { - //when an object is instantiated (wi

background : Recently in the study of teacher Han's notes are not very familiar with a single case and many examples, so through the Internet to find information on the way to learn.Design Patterns : The best practice is the software developers in the software development process faced with a general solution, that is, the experience of development summary.Singleton Mode (Singleton): is one of the simplest design patterns in

Basic concepts Ingleton is a creation model that ensures that only one instance is generated and provides a global access point to access it. For some classes, it is important to ensure that only one instance is available, such as when a database connection or Socket connection is limited, and only one connection must be maintained at the same time. For example, a set in a set cannot contain duplicate elements, and an object added to a set must be u

;public class Person {private static person person;p rivate person () {}public synchronized static person get () {I F (person = = null) {synchronized (person.class) {if [person = = null] {person = new person ();}}} return person;}}　　First, the person is not NULL, if NULL, the lock is initialized, and if not NULL, the person is returned directly. The entire design, double check.Advantages:1, to meet single-threaded one-case2, to meet the multi-threaded single case3, performance problems can be op

Reading Notes in objective java Article 3 use a private constructor or enumeration type to enhance the Singleton attribute and Reading Notes Singleton refers to the class that is instantiated only once. It is generally used to create classes that consume a lot of resources or require only one instance in the system. This is very common. I remember this interview

Java Project (5) -- Application and Research of Singleton Mode The Singleton mode is a very unique mode. Few people compare it with other modes, because the singleton mode is very simple and special, and its role is to ensure that a class has a unique instance, and make a global variable accessible. the method to ensur

void main (string[] args) {//TODO auto-generated method stubnested Sin Gleton; myrunnable mm = new myrunnable (); Myrunnable m1 = new myrunnable (); Myrunnable2 m2 = new Myrunnable2 (); new Thread (M1). Start (); new Thread (m2). Start (); if (M1.singleton = = M2.singleton) { //Is the same System.out.println ("is the same");} Else{system.out.println ("Not the Same");}}} Class Myrunnable implements runnabl

, delayed loading, and thread-safe (this avoids the creation of static instances when the Singleton class is loaded, and because static inner classes are only loaded once, this is also thread-safe:)Enumeration Notation Publicenum enumsingleton{INSTANCE;}Access via Enumsingleton test=enumsingleton.instanceThe use of enumerations, in addition to thread-safe and anti-reflection forced invocation of the constructor, also provides an automatic serializatio

Learning Java for more than a year, a lot of basic knowledge is understood, some know how to use, but do not understand, it is how to come.Often in the book to see the introduction class inside the construction method, static methods, common methods and static variables, call order, but do not understand its true usefulness.When I came into the company today, I suddenly thought of the Java class, the method

#模式设计# #1, default mode (also called default mode)# # #1.1-There is a monk interface, Monk interface methods have Chizhai, meditation, chanting, martial arts, and there is a LU Zhishen to achieve this interface, but he did not want to implement all the methods in the interface, he only want to use the monk interface in the martial arts method. What about this time?# # #1.2-Solution: Find an Intermediate class, this class can be an abstract class, or it can be a concrete class, let this class to

One. A hungry man, thread-safe.Package com.cal;public class SingleTon {1. Private construction method, do not promise new objectPrivate SingleTon () {}2. Provide yourself with a private static objectprivate static SingleTon instance = new SingleTon ();3. Provide a public static method to the outsidepublic static