43 Singleton Pattern

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Singleton:

ensures a class has only one instance, and provides a global point of access to it.

Java example 1:

public class Singleton {private static Singleton instance;private Singleton() {}public static Singleton getInstance() {if (instance == null) {synchronized (Singleton.class) {if (instance == null) {instance = new Singleton();}}}return instance;}}

Java example 2:

public class Singleton {private static Singleton instance = new Singleton();;private Singleton() {}public static Singleton getInstance() {return instance;}}

C# example1:

public class Singleton{    private volatile static Singleton _instance = null;    private static readonly object lockHelper = new object();    private Singleton(){}    public static Singleton CreateInstance()    {        if(_instance == null)        {            lock(lockHelper)            {                if(_instance == null)                     _instance = new Singleton();            }        }        return _instance;    }}

C# example 2:

public class Singleton{     private Singleton(){}    public static readonly Singleton instance = new Singleton();}