Design patterns in Java:
Strategy pattern, proxy pattern, singleton pattern, multiple instance pattern, factory method pattern, abstract factory Pattern, facade pattern, adapter pattern, template method pattern, builder pattern, bridge pattern, command pattern, decorator pattern, iterator pattern, composition pattern, observer pattern, chain of responsibility pattern, visitor pattern, state pattern, prototype pattern, Mediator mode, interpreter mode, Hengyuan mode, memo mode.
Example:
Single case mode
The so-called singleton design means that a class only allows one instantiated object to be generated. The best understood design pattern is divided into lazy man style and hungry man style.
Hungry Chinese style: The construction method is privatized. New instantiated objects cannot be generated externally. The instantiated objects can only be obtained through static methods.
class Singleton {
/**
* 在類(lèi)的內(nèi)部可以訪問(wèn)私有結(jié)構(gòu)，所以可以在類(lèi)的內(nèi)部產(chǎn)生實(shí)例化對(duì)象
*/
private static Singleton instance = new Singleton();
/**
* private 聲明構(gòu)造
*/
private Singleton() {
}
/**
* 返回對(duì)象實(shí)例
*/
public static Singleton getInstance() {
return instance;
}
public void print() {
System.out.println("Hello Singleton...");
}
}Lazy Chinese style: When using Singleton for the first time The operation of instantiating the object will only be generated when the object is created.
class Singleton {
/**
* 聲明變量
*/
private static volatile Singleton singleton = null;
/**
* 私有構(gòu)造方法
*/
private Singleton() {
}
/**
* 提供對(duì)外方法
* @return
*/
public static Singleton getInstance() {
// 還未實(shí)例化
if (singleton == null) {
synchronized (Singleton.class) {
if (singleton == null) {
singleton = new Singleton();
}
}
}
return singleton;
}
public void print() {
System.out.println("Hello World");
}
}Recommended tutorial: Java tutorial
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