單例、工廠、適配器、裝飾器
阿新 • • 發佈:2019-05-12
print oid col instance 工廠 void public font run
單例
單例分為懶漢式和餓漢式
1 public class Singleton { 2 3 4 //餓漢加載 5 //應用時才加載,節省內存 6 private static Singleton instance; 7 private Singleton() { 8 } 9 public static Singleton getInstance(){ 10 if (instance == null) { 11 synchronized(Singleton.class) { 12 if (instance == null) { 13 instance = new Singleton(); 14 } 15 } 16 } 17 return instance; 18 } 19 20 21 //餓漢加載 22 //浪費內存 23 // private static Singleton singleton=new Singleton();24 // public static Singleton getInstance(){ 25 // return singleton; 26 // } 27 28 public void run(){ 29 System.out.println("hellowolrd"); 30 } 31 }
工廠模式:
單例、工廠、適配器、裝飾器