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.
This guide 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.
Lessons
- Specifying the code to run on a thread
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Learn how to write code to run on a separate
Threadby defining a class that implements theRunnableinterface. - Creating a manager for multiple threads
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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
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Learn how to run a
Runnableon a thread from the thread pool. - Communicating with the UI thread
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Learn how to communicate from a thread in the thread pool to the UI thread.
More information
To learn more about multi-threaded operations on Android, see the following guides:
Sample app
To try out the concepts in this guide, download ThreadSample.