单例类
如果一个类始终只能创建一个实例,
1 class Singleton { 2 public static Singleton instance; 3 private Singleton() {} 4 public static Singleton getInstance() { 5 if (instance == null) { 6 instance = new Singleton(); 7 } 8 9 return instance; 10 } 11 } 12 13 public class SingletonTest { 14 public static void main(String[] args) { 15 Singleton s1 = Singleton.getInstance(); 16 Singleton s2 = Singleton.getInstance(); 17 18 System.out.println(s1 == s2); 19 } 20 }
使用单例类模式