几个不常用的Java关键字

native

声明外部实现的方法（C++,C）实现

transient

1.非持久化状态对象，持久化状态对象在archive对象时必须被保存.但是对于非持久化状态的对象在archive时则会忽略保存.
2.不能序列化

volatile
1.跟transient一样不能序列化
2.volatile 声明的变量不进行缓存，每次都能得到最新的值，这样在多线程环境中可以保证每次取到的值是最新的。（20081114添加--）



strictfp:
限制浮点运算来保证Java 程序 的夸平台性。

可以参考下面的材料:

What is the difference between Transient, Volatile and Strictfp?

Transient: The transient modifier applies to variables only and it is not
stored as part of its object's Persistent state. These variables are not
serialized. Transient instance fields are neither saved nor restored by the
standard serialization . You have to handle restoring them yourself.

Volatile: Volatile modifier tells the compiler that the variable modified by
volatile can be changed unexpectedly by other parts of the program. For
example a Variable might be read from Cache and not update the content if it
has been changed by another thread. Specifying a variable as volatile tells
the JVM that any threads using that variable are not allowed to cache that
value at all. Making the Variable Volatile will ensure that the compiler
will get the content of the variable every time it is used and not cache its
content. If not used Carefully this modifier might introduce bugs..

Strictfp : is used to restrict floating point calculations ( fp ) to ensure
portability ( platform Independent ). When this modifier is specified, the
JVM adheres to the Java specifications ( IEEE-754 floating-point
specification ) and returns the consistent value independent of the
platform. That is, if you want the answers from your code (which uses
floating point values) to be consistent in all platforms, then you need to
specify the strictfp modifier.