java isInstance instanceof isAssignableFrom

isInstance

1	B.class.isInstance(a)

动态等价，用于检查泛型，jdk中的CheckedMap里面用到这个检查Map里面的key、value类型是否和约定一样

instanceof

1	class1 instanceof class

class1是class的实例，class是类的或者接口，父类或父接口，即B b = a成立

isAssignableFrom

两个class类型关系判断，判断B是不是A的子类或子接口

1	a instanceof B

test

User: 用户基类
PublicUser extend User: PublicUser用户子类，继承User类

PublicUser prUser = new PublicUser();

#isintance
System.out.println(User.class.isintance prUser)       //true

System.out.println(prUser intanceof User)       //true

System.out.println(PublicUser.class.isAssignableFrom(User.class))       //true

System.out.println(User.class.isAssignableFrom(PublicUser.class))       //false