应用程序类是否在UI线程上运行？

Question

Sorry for being a newbie but i created a method in Application class in java, is it safe to run a method with complex to medium algorithm? is it going to be a hiccup in the UI's?

Answer 1

From Processes and Threads | Android Developers (emphasis mine):

When an application component starts and the application does not have any other components running, the Android system starts a new Linux process for the application with a single thread of execution. By default, all components of the same application run in the same process and thread (called the "main" thread). If an application component starts and there already exists a process for that application (because another component from the application exists), then the component is started within that process and uses the same thread of execution. However, you can arrange for different components in your application to run in separate processes, and you can create additional threads for any process.

And:

The system does not create a separate thread for each instance of a component. All components that run in the same process are instantiated in the UI thread, and system calls to each component are dispatched from that thread. Consequently, methods that respond to system callbacks (such as onKeyDown() to report user actions or a lifecycle callback method) always run in the UI thread of the process.

So yes, methods like onCreate in your Application class will be called on the main (UI) thread.

There are only a few classes that do start asynchronously, like the IntentService for example.

Answer 2

complex to medium algorithm

if it is complex, you should run it in an asynchronous way, using a Thread , an AsyncTask , an IntentService or whatever suits you better, but don't run it directly on the a subclass of Application / Activity / Fragment / Service or whatever runs on the UI Thread. It will slow down the start up of you application otherwise.

Answer 3

是的，从活动到广播接收器的所有应用程序组件都在ui线程上运行，仅当您必须执行一些长时间的提取任务或后台执行或网络提取时，才使用asynctask或intent服务在单独的线程中对其进行处理，以使它不会滞后您的用户界面屏幕。