Singleton mode--Single State mode

Single State mode:

To prevent a class of a single state pattern from being instantiated multiple times, you should set the constructor of the class to private, which guarantees that the class instance can only be obtained through a static method. And the static method guarantees

Each returned instance is the same, so that an instance of the class needs to be set as a class property, which can be set to static because it needs to be accessed by a static method

Property. Instances of a single State class are the same shared instance.

The sample code for a single state pattern is as follows:

public class Singletontest

{

int value;

private static Singletontest instance;

Private Singletontest ()

{

SYSTEM.OUT.PRINTLN ("Executing builder ...");

}

public static Singletontest getinstance ()

{

if (instance = null)

{

Instance = new Singletontest ();

}

return instance;

}

public int GetValue ()

{

return value;

}

public void SetValue (int value)

{

This.value = value;

}

public static void Main (string[] args)

{

singletontest T1 = singletontest.getinstance ();

Singletontest t2 = singletontest.getinstance ();

T2.setvalue (9);

System.out.println (T1==T2);

}

}