handler looper

message system and simple principle.Let's learn the fundamentals of the messaging system.The basic principle and composition of the two-message systemThe establishment of a generic message system model roughly consists of the following parts:L Message PrototypeL Message QueuingL Send a messageL message loopL Message AcquisitionL Message DistributionL Message ProcessingThe approximate model diagram is as follows:　　　　The message system model typically includes the above seven parts (message proto

Message: messages, which contain message IDs, message processing objects, and processed data, are unified by MessageQueue, and eventually handled by handler. Handler: Processor, responsible for message delivery and processing. When using handler, you need to implement the Handlemessage (Message msg) method to handle a particular message, such as updating the UI.

from the 2.3 Runtime is that the UI component is manipulated in a non-UI thread. No, Magic, Asynctask#onprogressupdate () and Asynctask#onpostexecute () documents clearly written that these two callbacks are in the UI thread, how to report such an exception! Cause AnalysisAsynctask designed to perform asynchronous tasks but can communicate with the main thread, it has an internal internalhandler is inherited from the handler static member Shandler,

Android's message processing has three core classes: Looper,handler and message. There's actually a message queue, but MQ is encapsulated in Looper, and we don't deal directly with MQ, so I don't use it as a core class. Here are the following:Thread of the magician LooperLooper literally means "circulator", which is designed to make a normal thread into a

first, take a look at the use of the process1. Using handler instances in child threads /*********** Child Threads Use Handler instance *********/ private class Looperthread extends thread {public Handler Handler; @Override public Void Run () { looper.prepare ();

A lot of people interviewed must have been asked, what is the relationship between Looper, Handler, and message in Android? The purpose of this blog is to introduce 3 relationships from the source point of view, and then give a conclusion that is easy to remember.1. Overview handler, Looper, and message all three conce

IntroductionWhen we do Android development, we often need to implement the asynchronous loading of images/Web pages/other. In fact, to implement asynchronous loading, you need to implement inter-thread communication, while in Android, using Handler, Looper, and Message enables different threads to communicate and complete asynchronous tasks. Although Android has provided us with the Asynctask class to accom

In the previous blog post, two typical instances of inter-thread communication based on the handler Looper mechanism in Android were given. In this paper, the basic principles of this mechanism are studied in depth. Personally think, learn Android programming the best teacher is the source code of Android, the following will be based on the Android-19 source for analysis, focusing on the analysis of ideas.T

Android Threading message passing mechanism--looper,handler,messageBefore introducing these concepts, let's look at the context in which these mechanisms are introduced.For performance optimizations, Android UI operations are not thread-safe (if you don't know what thread safety is, you can read Here's a question: What if your Android program wants to download a picture on the Web (we don't consider using A

Android's message processing has three core classes: Looper,handler and message. There's actually a message queue, but MQ is encapsulated in Looper, and we don't deal directly with MQ. Usually we use the most often is the message and handler, if the use of handlerthread or their own implementation of similar handlerthr

1. The relationship between Handler Looper MessageQueue2. Source Code AnalysisRepresents the relationship between the four classes of handler, Looper, MessageQueue, and message. The handler must be associated with a looper