In a previous article on Asynctask, we said at the end that Asynctask is using the handler's message asynchronous processing mechanism to return the results of the operation to the main thread with a message, thereby updating the UI thread.In our daily development work, Handler is also one of the classes that we often use, so what is the main role of
What is Handler used for?
1 Execution of Scheduled tasks, you can perform certain tasks at the scheduled time, you can simulate the timer
2) communication between threads. When the Android application starts, a main thread is created, and the main thread creates a message queue to handle the various messages. When you create a child thread, you can get the handler
Android message Handler and androidhandlerWhy does Android provide Handler?
Android recommends that you do not perform time-consuming operations in the UI thread, because this can easily cause ANR exceptions (in the Android source code, we can see that if the UI does not respond to user operations for more than 5 seconds, ANR exception will be reported ). Therefo
Android main thread's message system (Handler \ lofter), androidlo
Preface:
Previous articles have written about Bitmap and memory optimization technologies. This article will talk about Handler.
Handler is an important knowledge in the Android system. It is often asked during the Android multi-thread interview and oft
In the previous article, we talked about the method of calling handler in the SendMessage, and eventually we would go into a way called Sendmessageattime, as follows: public boolean sendmessageattime (Message msg, long Uptimemillis) { MessageQueue queue = mqueue; if (queue = = null) { runtimeexception e = new RuntimeException (this + "sendmessageattime () calle
The role of handler is to send a message and handle the message sent by Message,handler is actually sent to its own object for processing, so who is sent who is handling, but this absolutely makes sense, So that we can move the processing of the
There are many and thorough descriptions of this topic on the Internet, such:
Http://www.cnblogs.com/xirihanlin/archive/2011/04/11/2012746.html
Http://disanji.net/2011/01/23/android-looper-handler-thread/
Http://zhoujianghai.iteye.com/blog/1097156
In the process of using handler, the following should be the most:
Mhandler. sendmessage (MSG,...); (1)
Mhandler. Post (mrunnable); (2)
I believe that the first
The concept of 1,handlerWhat is Handler used for?1) Perform scheduled tasks, perform certain tasks at scheduled times, and can simulate timers2) Inter-thread communication. When the Android app starts, a main thread is created, and the main thread creates aMessage Queuing to process various messages. When you create a child thread, you can get the parent thread in your child threadCreates a handler object t
http://blog.csdn.net/caesardadi/article/details/8473777When the application starts, it opens a main thread (the UI thread), which manages the UI, listens for user clicks, responds to users, and distributes events. Therefore, generally in the main thread do not perform more time-consuming operations, such as network download data, or a ANR error. Therefore, these operations are placed in child threads, but because the androidui thread is unsafe, the UI can only be updated in the main thread.
Handler message transmission mechanism (1)
Why Handler:
For the sake of performance optimization, Android UI operations are not thread-safe, which means that if multiple threads operate the UI components concurrently, thread security problems may occur. To solve this problem, Android has developed a simple principle: only allow the UI thread (that is, the main th
Android Basics Getting Started tutorial--3.3 handler message passing mechanism analysistags (space delimited): Android Basics Getting Started TutorialIntroduction to this sectionIn the first two sections we learned about two kinds of event-handling mechanisms in Android, both of which respond to events, and this section explainsIs the information passing handler
There are various events in the android activity, which are eventually converted to messages for processing. The message system in Android involves:* Message sending* Message Queue* Message loop* Message distribution* Message read
Handler is a class that is used to manipulate message queues within a thread. It's a bit round, it's okay, let's take it slow. The previous looper mentioned that Looper is used to create message queues for threads, that is, looper can allow Message Queuing (MessageQueue) to be attached to a thread, and let
To add a message handler function to a controlCreating a dialog class and adding a control variable in the previous lecture, the main content of this lecture is how to add a message handler function to a control.MFC defines a number of messages for dialog boxes and controls, and we trigger messages when they are manipu
Before starting this article, let's summarize some of the key points in the first two articles about handler, Looper, and MessageQueue:0) before creating handler in thread, you must first call Looper.prepare (), create a thread local variable looper, and then call Looper.loop () to go round.1) When handler is created, it is possible to call handler's Sendmessagea
Recently found some information about the communication between Android threads, organized and learned a bit, and made a simple example.Andriod provides Handler and Looper to meet the communication between threads. For example, a sub-thread downloads a picture from the network and sends a message to the main thread when it is downloaded, and this message is passe
Android Asynchronous Message Processing Mechanism (1) basic use of Handler
The Android UI is thread-safe. If you try to perform UI operations in the Child thread, the program may crash. The solution should be to create a Message object, and then use Handler to send it out, and then get the
Parse Android Message Processing Mechanism
-- Handler/thread/logoff messagequeue
Tian haili @ csdn
Keywords: Android message handlerthread low.uml
This article explains how Android uses handler/thread/logoff and messagequeue to implement the internal implementation of the mess
message pool. If yes, It is retrieved and returned. If no message instance is available in the message pool, a message object is created with the given parameters. When removemessages () is called, the message is deleted from the messag
Android Handler logoff and MessageQueue message mechanism Principle
Android message processing class:
Logoff, Handler, MessageQueue, Message, ThreadLocal, ThreadLocal. Values, and HandlerThread.Logoff: the thread does not have a message
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