永远不要忘记最基础的东西，只有把最基础的知识打牢靠，才能够使你走的更远，我将从今天开始，进行线程知识的回顾，一些常用知识点，以及java1.5 引入的并发库，进行详细的讲解与总结
创建线程的目的是为了开启一条执行路径，去运行指定的代码；
java 对线程的创建java.lang包下，我们先看关于Thread 源码文档，看它对Thread 有什么解释呢？
* A <i>thread</i> is a thread of execution in a program. The Java * Virtual Machine allows an application to have multiple threads of * execution running concurrently. * <p>
翻译：
线程是程序中的执行线程，Java 虚拟机 允许应用的程序去使用多个线程并发的去执行运行 * Every thread has a priority. Threads with higher priority are * executed in preference to threads with lower priority. Each thread * may or may not also be marked as a daemon. When code running in * some thread creates a new <code>Thread</code> object, the new * thread has its priority initially set equal to the priority of the * creating thread, and is a daemon thread if and only if the * creating thread is a daemon. 翻译：
每一个线程都是有优先级的，线程高的优先级优于线程低的优先级，每一个线程可以或者不可以标记为一个守护线程
当一个线程中运行创建了一个新的线程对象，这个新线程的优先级初始值等于创建它的线程的优先级，当创建线程是守护线程的
时，新线程才是守护程序
* When a Java Virtual Machine starts up, there is usually a single * non-daemon thread (which typically calls the method named * <code>main</code> of some designated class). The Java Virtual * Machine continues to execute threads until either of the following * occurs: * <ul> * <li>The <code>exit</code> method of class <code>Runtime</code> has been * called and the security manager has permitted the exit operation * to take place. * <li>All threads that are not daemon threads have died, either by * returning from the call to the <code>run</code> method or by * throwing an exception that propagates beyond the <code>run</code> * method.
翻译：
当Java 虚拟机 启动的时候，通常都会有单个非守护线程（代表性的他会调用某个类的main 方法）Java 虚拟机会一直运行
知道下面的情况发生
1.使用了runtime 类的exit 方法，并且安全管理器允许退出操作发生
2.非守护线程中的线程停止运行，都会抛出传播到run方法之外的的异常
线程创建的两种方式：官方都有了明确的demo
* There are two ways to create a new thread of execution. One is to * declare a class to be a subclass of <code>Thread</code>. This * subclass should override the <code>run</code> method of class * <code>Thread</code>. An instance of the subclass can then be * allocated and started. For example, a thread that computes primes * larger than a stated value could be written as follows:
翻译：
声明一个继承Thread 的子类，这个子类应该去覆盖run 方法，这个子类的实例会被分配和启动；下面是例子：
* <hr><blockquote><pre> * class PrimeThread extends Thread { * long minPrime; * PrimeThread(long minPrime) { * this.minPrime = minPrime; * } * * public void run() { * // compute primes larger than minPrime * . . . * } * } * </pre></blockquote><hr> * <p> * The following code would then create a thread and start it running: * <blockquote><pre> * PrimeThread p = new PrimeThread(143); * p.start(); * </pre></blockquote> * <p> * The other way to create a thread is to declare a class that * implements the <code>Runnable</code> interface. That class then * implements the <code>run</code> method. An instance of the class can * then be allocated, passed as an argument when creating * <code>Thread</code>, and started. The same example in this other * style looks like the following:
翻译：
另一种方式是声明一个实现runnable 接口的类，然后实现run 方法，这个实例会被分配
在创建线程时候，它会被传递作为一个参数，然后start ，下面是例子
* <hr><blockquote><pre> * class PrimeRun implements Runnable { * long minPrime; * PrimeRun(long minPrime) { * this.minPrime = minPrime; * } * * public void run() { * // compute primes larger than minPrime * . . . * } * } * </pre></blockquote><hr> * <p> * The following code would then create a thread and start it running: * <blockquote><pre> * PrimeRun p = new PrimeRun(143); * new Thread(p).start(); * </pre></blockquote> * <p> * Every thread has a name for identification purposes. More than * one thread may have the same name. If a name is not specified when * a thread is created, a new name is generated for it. * <p> * Unless otherwise noted, passing a {@code null} argument to a constructor * or method in this class will cause a {@link NullPointerException} to be * thrown.
在下一节，我们对官方提供对两种方式进行实例编写