kaixinbingju的专栏

system-level alarms.you can’t guarantee that it’ll still be running at that point in the future.To ensure that our code is executed at the desired time, we can’t rely on the Service because the OS

The ContentProvider API is a thin layer on top of a SQLite database.This example showcased using the ContactsContract provider. The android.provider package also contains providers for the calendar

You need to send a request with data to another application, or you need to send a response to a request from another application. The application making the requestwill cede control to another appl

it’s crossplatform(it’s a Firefox browser extension), open source, and free.

The first Activity in FileExplorer is a screen that allows users to choose whether to work with the internal or external storage.If the user chooses the internal storage path, we then go to an Act

You want to execute a delayed task that executes its logic only after a certain amount of time has passed.The splash image can be dropped in the res/drawables folder:splash.pngThe layout for a

Any configuration change will terminate the currently visible Activity and restart it using the new system configuration, so always be prepared for interruptions.You need to perform tasks asyn

It’s important to think about the effect that the preceding code will have on battery life. The CPU is going to be woken up to make a network call, update a local database,and possibly create Notifi

Caching of data can make a huge difference in the performance of any application.You want to centralize the access to this data in one place and cache it, since retrieving it over the network is slo

AlarmManager help us to resurrect our killed Service. But that resurrection could be short-lived.the Service needs to do—retrieve fresh stock data from the Internet and send out Notifications if neede

AsyncTask offers an easy-to-use (but more limited).You need to perform an asynchronous job that follows a pre-process/process/postprocess pattern, and are looking for a code template that allows y

You want to store data on the external storage. Also, you want to be able to easily determine when the external storage is and isn’t available.create layout file external_storage.xml<LinearLa

Realizing that HTTP requests can fail when the user is on the move, you want to put a proper request-retry system in place so that when a request fails because of a flaky network,you can silently rese

explicitly move forward through an XML document bit by bit, and skip any entity you encounter in which you’re not interested. That’s what a pull parser does.You’re looking for a lightweight way to p

The Apache HTTP Components are composed of two parts: HttpCore, a set of lowlevel classes for handling HTTP connections, and HttpClient, a more high-level set ofclasses built on top of HttpCore, whi

You need to perform simple networking tasks via HTTP, such as downloading a file, and you want to avoid the performance penalty imposed by the more high-level, much larger and more complex Apache Http

we must send data across process boundaries. The first and most common way of doing this is by using Intents.

Because our DAOs are each unaware of any table other than their own, we’re also going to create a DataManager interface, an implementation class that will wrap themultiple DAOs and take care of the

You want an easy way to store simple information, such as strings and primitive values.You can use SharedPreferences to easily store and retrieve data.SharedPreferences prefs = getSharedPreference

You need to guarantee that file data is written to disk immediately, regardless of the filesystem in use and the platform version.Syncing ensures that the buffer catches up with the physical disk.You

How do you determine whether a certain provider is enabled? And if not enabled, how do you prompt the user to enable that provider because your application may require it?A LocationListener is simpl

The LocationManager class is the gateway into all the location related services on Android. It’s a system service that allows you to access location providers, set up locationupdate listeners and pr

You’re writing an application in which several threads must exchange messages, as in a producer-consumer scenario.We’ve already seen how to bind a handler and use it to send messages. The interestin

every list item is created in the list adapter’s getView method, and this method is called whenever you scroll the list to see more items. We could use this method to spawn a thread that downloads the

The Ajax (Asynchronous JavaScript and XML).You either want to integrate with a web service that only supports JSON, or you want to take advantage of JSON’s benefits such as being able to efficiently

Android bundles three different kinds of parser APIs(DOM, SAX, and XmlPull).whether they need to load the entire XML document into memory up front. Parsers based on the Document Object Model (DOM) d

A web service is a set of server-side interfaces exposed on the Internet using web technologies such as HTTP for data transfer or XML and JSON for data serialization. Unlike web sites, web services ar

Main Application, Main Process, Main Service,Main Task,Main Activity vs Multiply Applications,Multiply Processes,Multiply Services,Multiply Tasks, Multiply ActivitiesThe way to fully implement multi

(1)ViewHolder pattern, which will make your list render significantly faster and hence scroll more smoothly.(2) Adapter,  the views for our ListView are bound to the data source we’ll use a static

In essence, cursors iterate over result sets and provide access to data one row at a time.first,We’ll want simple model objects,second,we  need create table class with static methods and OpenSql

You have two or more applications that are closely related and depend on each other. You want them to share private resources such as files or code that must not be visibleto other applications, but

In any event, you must somehow get hold of these settings, and be notified when, for example, the proxy server changes while your application is running, so that you can update HttpClient to send requ

If you plan to develop applications that only target Android 2.2 or newer, you may consider skipping this technique.You’re running threads that need to communicate with a web server through a single

AndroidManifest.xml<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="example.autoform" android:versionCode="1" android:versionName="1.0" > <uses-sdk

You need to pass data to another app so that it can perform some operation on that data and return a result back to your app. You don’t want to give up control flow to this other application; you want

by design it’s impossible to update user interface elements from outside the main UI thread.if you’re sharing state between two or more threads you always need to synchronize this shared data usin

After clicking the button that initiates the download, Android will give your application no more than a few seconds to respond to that input event. Otherwise, it’ll kill it and raise the previously m

you can run services in separate processes, but that isn’t a requirement. In fact, unless you specify a process ID explicitly, they won’t.one golden rule about user interfaces is to always remain re

Having the caching data in the background Service allows that Service to do other things with that data. A common example of this is to create notifications based on the data that’s retrieved from the