(26) How to use Handler Class to update the UI Thread

在android中系统不允許在非Main Thread更新UI。當我們在非主線程做了耗時操作後，需要去更新UI的時候，我們就需要使用Handler來執行更新操作。

A Handler in Android is used to send and process messages between threads. It allows you to schedule code to run at a later time, to run code on ...

To handle more complex interactions with a worker thread, you might consider using a Handler in your worker thread to process messages delivered ... Processes · Threads · Worker threads · Thread-safe methods

一般是用來處理大量數據或者長時間運算最後再利用Activity 內建的方法runOnUiThread 呼叫main thread handler 幫忙處理UI 部分。 第二種寫法是自己定義 ...

目的是為了讓Message 能夠作緩衝，好讓Message先暫存起來。因此，當Message 已經被放在其它Thread上的MessageQueue 之後,它裡面包著Handler,而Handler上的callback function ...

handler被Create在Activity，這也就是說這一個Handler已經跟UI Thread綁訂了，所以說他可以做有關UI的事情，這時候重點來了，把Handler設定到自己定義的 ...

假設目前的thread已經是在UI thread中，Runnable會立即的去執行。否則會透過UI thread的MessageQueue 排隊，此方法如下： new Handler(Looper.getMainLooper()).post(runnable);.

Because if you create a handler in a non UI thread you will post messages to the non UI Thread. A handler by default post message to the thread ...

I am working on an android application, that fetches image from Internet and show in the user interface. I am using RecyclerView for showing the image.

Fundamentally, Handlers and Loopers is the base mechanism for communication between threads in Android OS, all other async tools that post ...