android.os.Handler allows us to send and process Message and Runnable objects associated with a thread’s MessageQueue. Each Handler instance is associated with a single thread and that thread’s message queue.<\/p>\n
Handler used for:<\/p>\n
Construction Of Handler<\/strong><\/p>\n [java] [java] Message creation<\/strong> [java] Inserting messages into the queue<\/strong><\/p>\n [java] [java] [java] Processing Message<\/strong> There is Runnable object, not data.<\/p>\n [java] There is data,not Runnable object. Processing on messsage is performed inside of Handler.handleMessage()<\/em>.<\/p>\n [java] handler.sendMessage(message); Removing Messages from the Queue<\/strong> Message Identifiers<\/p>\n There are the following method which is used for managing the queue –<\/p>\n [java] [java] [java] How to Trace the message queque processing ?<\/strong><\/p>\n [java] Let\u2019s look at an example of tracing a message<\/p>\n [java] output of this code is<\/p>\n [java] android.os.Handler allows us to send and process Message and Runnable objects associated with a thread’s MessageQueue. Each Handler instance is associated with a single thread and that thread’s message queue. Handler used for: Message creation Inserting messages into the queue Processing messages on the consumer thread Managing messages in the queue Construction Of Handler By […]<\/p>\n","protected":false},"author":126,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"iawp_total_views":30},"categories":[518,1],"tags":[2086,2088,2085,2087],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.tothenew.com\/blog\/wp-json\/wp\/v2\/posts\/24756"}],"collection":[{"href":"https:\/\/www.tothenew.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.tothenew.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.tothenew.com\/blog\/wp-json\/wp\/v2\/users\/126"}],"replies":[{"embeddable":true,"href":"https:\/\/www.tothenew.com\/blog\/wp-json\/wp\/v2\/comments?post=24756"}],"version-history":[{"count":0,"href":"https:\/\/www.tothenew.com\/blog\/wp-json\/wp\/v2\/posts\/24756\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.tothenew.com\/blog\/wp-json\/wp\/v2\/media?parent=24756"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.tothenew.com\/blog\/wp-json\/wp\/v2\/categories?post=24756"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.tothenew.com\/blog\/wp-json\/wp\/v2\/tags?post=24756"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}\n
\n
\n new Handler();
\n new Handler(Handler.Callback)
\n [\/java]<\/p>\n\n
\n
\n new Handler(Looper);
\n new Handler(Looper, Handler.Callback);
\n [\/java]<\/p>\n
\nThere is a list of methods that will help to create Message<\/p>\n
\nMessage obtainMessage(int what, int arg1, int arg2)
\nMessage obtainMessage()
\nMessage obtainMessage(int what, int arg1, int arg2, Object obj)
\nMessage obtainMessage(int what)
\nMessage obtainMessage(int what, Object obj)
\n[\/java]<\/p>\n\n
\n
\n boolean post(Runnable r)
\n boolean postAtFrontOfQueue(Runnable r)
\n boolean postAtTime(Runnable r, Object token, long uptimeMillis)
\n boolean postAtTime(Runnable r, long uptimeMillis)
\n boolean postDelayed(Runnable r, long delayMillis)
\n [\/java]<\/p>\n\n
\n
\n boolean sendMessage(Message msg)
\n boolean sendMessageAtFrontOfQueue(Message msg)
\n boolean sendMessageAtTime(Message msg, long uptimeMillis)
\n boolean sendMessageDelayed(Message msg, long delayMillis)
\n [\/java]<\/p>\n\n
\n
\n boolean sendEmptyMessage(int what)
\n boolean sendEmptyMessageAtTime(int what, long uptimeMillis)
\n boolean sendEmptyMessageDelayed(int what, long delayMillis)
\n [\/java]<\/p>\n
\nMessage is dispatched by the looper and deliver to Handler. Handler is received this message and process it. Processing Operation is done at the consumer thread for which handler is belong.<\/p>\n\n
There are two type of message in Message<\/p>\n
\n handler.post(new Runnable() {
\n @Override
\n public void run() {
\n \/\/TODO : Do some operation
\n }
\n });
\n [\/java]<\/p>\n\n
\n
\n final Handler handler = new Handler() {
\n @Override
\n public void handleMessage(Message message) {
\n \/\/TODO : Get the data from Message and perform opertation accordingly.
\n }
\n };<\/p>\n
\n [\/java]<\/p>\n
\nWhen we talk about removing something, The first thing that comes in our mind is that what is the identifier for it?<\/p>\n\n\n
\n Identifier<\/th>\n Description<\/th>\n Messages to which it applies<\/th>\n<\/tr>\n \n Handler<\/td>\n Message receiver<\/td>\n Both task and data messages<\/td>\n<\/tr>\n \n Object<\/td>\n Message tag<\/td>\n Both task and data messages<\/td>\n<\/tr>\n \n Integer<\/td>\n what<\/em> parameter of Message<\/td>\n Data messages<\/td>\n<\/tr>\n \n Runnable<\/td>\n Task to be executed<\/td>\n Task messages<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n \n
\n
\n removeCallbacks(Runnable r)
\n removeCallbacks(Runnable r, Object token)
\n [\/java]<\/p>\n\n
\n
\n removeMessages(int what)
\n removeMessages(int what, Object object)
\n [\/java]<\/p>\n\n
\n
\n removeCallbacksAndMessages(Object token)
\n [\/java]<\/p>\n
\n Looper.myLooper().setMessageLogging(new LogPrinter(Log.DEBUG, TAG));
\n [\/java]<\/p>\n
\n handler.post(new Runnable() {
\n @Override
\n public void run() {
\n Log.d(TAG, "Executing Runnable");
\n }
\n });
\n mHandler.sendEmptyMessage(111);
\n [\/java]<\/p>\n
\n Dispatching to Handler (android.os.Handler) {8226ef40} com.shim.handlertest.activities.HandlerMessageActivity$1@46590829: 0
\n Executing Runnable
\n Finished to Handler (android.os.Handler) {8226ef40} com.shim.handlertest.activities.HandlerMessageActivity$1@46590829
\n [\/java]<\/p>\n<\/blockquote>\n","protected":false},"excerpt":{"rendered":"