Android Developer: Heap Viewer demonstration
This demo shows the basic usage of the Heap Viewer tool. Heap Viewer reports in real time what type of objects, how many objects, and their size in Heap memory have been allocated to your application.
Its advantages:
Get the feeling of how your application allocates and re
ObjectiveRecently read this article, "Android UI performance Optimization", which uses the hierarchy viewer to optimize the layout. The development of Android so long, has been heard this tool, but never really go to use, have to say is a failure. Now just take advantage of the idle, study the use of Hierarchy Viewer.Start An
There have been a lot of articles on how the Hierarchy Viewer is used, and here is a step-by-step demonstration of how to use it, Ddna's "Android Tool" ignored UI Viewer: Hierarchy Viewer and Zhang Xingye's Android UI Optimization-The use of the Hierarchyviewer tool is great
[Android-007] [network image Viewer]
Network Image Viewer
Determine the image URL to send an http request
URL url = new URL (address); // gets the connection object and does not establish a connection HttpURLConnection conn = (HttpURLConnection) url. openConnection (); // set connection and read timeout conn. setConnectTimeout (5000); conn. setReadTimeout (5000)
implement this topic interface functionalityHere, I omitted the other code in the project, leaving only a frame structure. So our observer class is created.3. Create the Observer interface to define the functions that the viewer will implement.4. Create our Observer class:Realizing our well-defined observer interface becomes an observer.At this point, the framework of the entire observer pattern is built, so long as the business logic we want is impl
we can see, when setting up Adapter, a adapterdatasetobserver is constructed, that is, the observer, and finally, the Observer is registered to Adapter.Here we know that when the data of the ListView changes, call Adapter's Notifydatasetchanged () method, which again calls the Datasetobservable notifychanged () method, This method calls the OnChanged () method of all observers (Adapterdatasetobserver), and in the OnChanged () method calls the ListView re-layout method so that the ListView refre
NewIllegalArgumentException ("The observer is null."); } synchronized (mobservers) {if(Mobservers.contains (Observer)) {Throw NewIllegalStateException ("Observer"+ Observer +"is already registered."); } MOBSERVERS.ADD (Observer); } } /** * Removes a previously registered observer. The observer must not being null and it * must already has been registered. * @param observer The Observer to unregister * @throws ILLEGALARGUMENTEXCEPTION The Observer is NULL * @throws ILL Egalstate
notified through the Getcontentresolver (). Notifychange () method.The registration and notification here is obviously not in a process, for example, in a application through the CONTENTRESOLVER registered observer, in the B application through the Contentresolver notify the Observer, The contentresolver here is not a Contentresolver object in a, and is not able to be notified by a direct call. This is actually the event registration and notification through inter-process calls. The registratio
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Second, the required technology
Network requests
JSON parsing
Third, actual combat projects:3.1 Front-desk interface: It's easy to put a code on it. Obtain ID information by entering the ID number.3.2 Background Control initialization:3.3 Network Requests1. Use the Network debugging tool to find that the JSON returns the following structure:2. Using object-oriented thinking, we create the corre
1. Content ViewerDoes not belong to the four components, only the content provider ContentProvider corresponding small function.If the contents of the database are found to be changed, they will be observed immediately.Here is the logical diagram:When the data inside the bank in a application changes, the A application sends the data to a piece of public memory, and the memory watcher reads the data in the public memory. So that the database of a application is changed.This mechanism is similar
the Observer List of the Observer object Observable.addobserver (OBSERVER1); Observable.addobserver (OBSERVER2); Observable.addobserver (OBSERVER3); Observable.addobserver (OBSERVER4); //release message observable.postnewpublication ( "new");} Output Result:test4, update:newtest3, update:newtest2, update:newtest1, update:newYou can see that all observers subscribed to the observer have received the update message, and a one-to-many subscription-publishing system is complete.Application scena
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