Singleton mode in Design Mode

Singleton

It is a creation-type design model. It maintains only one object in a class and has only one object in life, such as the Earth, the Sun, and the universe. A singleton can also be used to set a class as a singleton without changing the object information.

There are two methods for singleton: lazy and ELE. Me.

Implementation of singleton:

Step 1: Change the constructor to private

Step 2: Use this class object as the static property of this class.

Step 3: use static methods to obtain static attributes of the class

The Code is as follows:

Lazy style (Kaige upgraded version ):

Advantage: Memory saving. If this object is not used, the memory will not be wasted.

Disadvantage: the invocation is slow.

Package com.cn. xfonlineclass2;

Public class dog {

Private string name;

Private int age;

Private string sex;

Private Static dog = NULL;

Private dog (string name, string sex, int age ){

This. Name = Name;

This. Age = age;

This. Sex = sex;

}

Public static dog getdog (){

If (dog = NULL ){

Synchronized (dog. Class ){

If (dog = NULL ){

Dog = new dog ("trademanager", "female", 4 );

}

}

}

Return dog;

}

Public String tostring (){

Return "name:" + name + "\ t Gender:" + sex + "\ t age:" + age;

}

}

 

Hungry Chinese style:

Advantage: the access is fast and the fastest way to get new objects.

Disadvantage: If no object is needed, the memory will be occupied, resulting in a waste of memory.

Package com.cn. xfonlineclass2;

Public class dog {

Private string name;

Private int age;

Private string sex;

Private Static dog = new dog ("", "Xiong", 3 );

Private dog (string name, string sex, int age ){

This. Name = Name;

This. Age = age;

This. Sex = sex;

}

Public static dog getdog (){

Return dog;

}

Public String tostring (){

Return "name:" + name + "\ t Gender:" + sex + "\ t age:" + age;

}

 

}

 

Test class:

Package com.cn. xfonlineclass2;

 

Public class test {

Public static void main (string [] ARGs ){

System. Out. println (dog. getdog ());

}

}

 

Note: The main method should be separated from the class to be tested. If you create a main method in the class to be tested, it means that you can access private variables in this class.