/* * 單例設計模式 * 確保類最多隻有一個實例,並提供一個全局訪問點 * * */ public class SinglePattern { private volatile static SinglePattern instance = null; private SinglePattern(){ } public static SinglePattern getInstance(){ if (instance==null){ synchronized (SinglePattern.class){ if (instance ==null){ instance = new SinglePattern(); } } } return instance; } }