Detailed analysis of singleton pattern in Java about lazy style and hungry style

This article mainly introduces the relevant information of java singleton mode. Here are examples of lazy man style and hungry man style. Friends who need it can refer to it

java singleton mode

The singleton pattern is a commonly used software design pattern. A special class that contains only one instantiated singleton in its trusted structure. Through the singleton design pattern, a class in the entire system can have only one instance.

The singleton design pattern is divided into two methods, the lazy man style and the hungry man style.

(1) Lazy style, that is, this singleton will be initialized only when getInstance is called.

(2) Hungry Chinese style, that is, once the class is loaded, the singleton initialization is completed. That is, when getInstance is called, the singleton already exists.

The code is as follows:

Lazy Chinese style singleton

/**
 * Description:
 * 一、设计了一个懒汉式单例
 * 
 * @author lee
 * */
public class SingleMode {

  public static SingleMode s = null;
  /**
   * Description:
   * 私有化构造函数
   * 
   * */
  private SingleMode(){} 

  /**
   * Description:
   * 提供一个方法来获取该单例
   * 
   * @return s 返回一个单例
   * */
  public static SingleMode getInstance(){

    //保证了线程安全，又减轻了资源加载和性能上的负担
    //即是在创建一次对象后，不再需要线程锁了。
    if(s==null){
      synchronized(""){
        if(s==null){
          s = new SingleMode();
        }
      }
    }

    return s;
  }

}

Hungry Chinese style Singleton

##

/**
 * Description:
 * 二、设计了一个饿汉式单例
 * 
 * @author lee
 * */
class SingleMode1{
  public static final SingleMode1 s = new SingleMode1();

  /**
   * Description:
   * 私有化构造函数
   * 
   * */
  private SingleMode1(){}

  /**
   * Description:
   * 提供一个方法来获取该单例
   * 
   * @return s 返回一个单例
   * */
  public static SingleMode1 getInstance(){
    return s;
  }

}

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