The speed and efficiency of a long-running, data-intensive operation often improves when you split it into smaller operations running on multiple threads. On a device that has a CPU with multiple processors (cores), the system can run the threads in parallel, rather than making each sub-operation wait for a chance to run. For example, decoding multiple image files in order to display them on a thumbnail screen runs substantially faster when you do each decode on a separate thread.
当你将一个需要长时间运行的，聚焦于数据的操作，分割成一些小的操作，并且在多线程中运行的话，那么这个长时间运行的操作的速度和效率将会提升不少。对于一个有多核的设备，系统可以并发的运行多个线程，而不是让每个子操作等到被执行。比如，当你要解码多张图片，以在屏幕上显示的话，你如果将每一个图片的解码操作放在每一个独立的线程的话，那么速度将会很快。
This class shows you how to set up and use multiple threads in an Android app, using a thread pool object. You’ll also learn how to define code to run on a thread and how to communicate between one of these threads and the UI thread.
本课程将会向你展示，如何通过一个线程池对象，来创立和使用多线程。你同样也会学到如何使得代码在线程中宇星，以及这些线程如何与主线程通信。
Lessons
- Specifying the Code to Run on a Thread
- Learn how to write code to run on a separate
Thread, by defining a class that implements theRunnableinterface. - Creating a Manager for Multiple Threads
- Learn how to create an object that manages a pool of
Threadobjects and a queue ofRunnableobjects. This object is called aThreadPoolExecutor. - Running Code on a Thread Pool Thread
- Learn how to run a
Runnableon a thread from the thread pool. - Communicating with the UI Thread
- Learn how to communicate from a thread in the thread pool to the UI thread.
