第一种同步
public class Singleton {
private static Singleton instance;
private Singleton() {
}
public synchronized static Singleton getInstance() {
if (instance == null) {
instance = new Singleton();
}
return instance;
}
}
第二种静态初始化
public class Singleton {
private static Singleton instance = new Singleton();
private Singleton() {
}
public static Singleton getInstance() {
return instance;
}
}
第三种静态holder类
public class Singleton {
private Singleton() {
}
private static class SingletonHolder {
public static Singleton instance = new Singleton();
}
public static Singleton getInstance() {
return SingletonHolderinstance;
}
}
