Android Development Network and Touch problem solving method

Go ahead and tidy up some of the problems and techniques you've encountered in the Android development process.

1.4.0 or more versions of Android cannot be networked in the main thread
The Android application runs in a Dalvik virtual machine process, which starts with a main thread (Mainthread) that, in Android 4.0 or later, enforces time-consuming network operations on the main thread, and if network operations are required, You need to create additional threads or use Asynctask, as described below is another way to develop threads.

The code is as follows	Copy Code
@Override protected void OnCreate (Bundle savedinstancestate) { Super.oncreate (savedinstancestate); Setcontentview (R.layout.single); New Thread (Postload). Start (); } Runnable postload = new Runnable () { @Override public void Run () { TODO auto-generated Method Stub To perform networking operations here } };

However, after networking operations generally need to update the UI based on networked data, a new problem arises, and the main thread is responsible for handling UI-related operations, so the main thread is called the UI thread. Android, which uses the UI single-threaded model, operates on the UI elements in the main thread, and the UI does not operate directly on it, and an error is made.

To solve this problem, you need to use the Android message loop mechanism to achieve communication between threads. That is, a non-UI thread sends a message to the UI thread, allowing the UI threads to manipulate the UI. For example, you can use the Post method of View to tell the UI thread to perform an operation to update the UI.

The code is as follows	Copy Code
Runnable postload = new Runnable () { @Override public void Run () { TODO auto-generated Method Stub Internet Access data TextView textshow = (TextView) Findviewbyid (r.id.show); Textshow.post (New Runnable () { @Override public void Run () {//This method will execute on the UI thread Textshow.settext (data); } }); } };

2. Detect if there is a network

code is as follows

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Final Connectivitymanager mconnectivity = (connectivitymanager) getsystemservice (Context.connectivity_service); Check network connection, if no network is available, do not need to do networking operations, etc. Networkinfo info = Mconnectivity.getactivenetworkinfo (); if (info!= null) {//If there is a network Determining the type of network connection int nettype = Info.gettype (); int netsubtype = Info.getsubtype (); if (NetType = = Connectivitymanager.type_wifi) { If the WIFI else if (NetType = connectivitymanager.type_mobile && Netsubtype = = Telephonymanager.network_type_umts) { If the 3G } else { Other network } else {//If no network }

3. Custom touch Create right and left stroke detection

The code is as follows

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Define gesture Speed Recorder Private Velocitytracker Velocitytracker; Define the distance between gesture action two points private static final int velocityx = 900; private static final int velocityy = 800; WebView postcontent = (webview) Findviewbyid (r.id.postcontent); Postcontent.setontouchlistener (New Ontouchlistener () { @Override public boolean Ontouch (View arg0, motionevent arg1) { TODO auto-generated Method Stub Switch (arg1.getaction ()) { Case Motionevent.action_down: if (Velocitytracker = = null) { Gets the speed at which gestures are sliding on the screen Velocitytracker = Velocitytracker.obtain (); Velocitytracker.addmovement (ARG1); } Break Case Motionevent.action_move: if (Velocitytracker!= null) { Velocitytracker.addmovement (ARG1); } Break Case Motionevent.action_cancel: Case Motionevent.action_outside: Break Case MOTIONEVENT.ACTION_UP: int Velocityx = 0, velocityy = 0; if (Velocitytracker!= null) { Velocitytracker.addmovement (ARG1); Velocitytracker.computecurrentvelocity (1000); Calculate how many pixels to slide per second Velocityx = (int) velocitytracker.getxvelocity (); Finally compute the retrieval X speed Velocityy = (int) velocitytracker.getyvelocity (); Finally compute the search Y speed } Stroke from right to left if (Velocityx <-velocityx && Velocityy < velocityy && velocityy >-velocityy) { Perform the appropriate action return true; else if (Velocityx > Velocityx && velocityy < velocityy && velocityy >-velocityy) {//From left to right Perform the appropriate action return true; } else { To judge if it is not a stroke operation, return false using WebView's own touch handling return false; } } return false; } });

In the detection process found that the touch is not complete (such as too little stroke distance, or touch the screen), or directly to determine the operation is not a stroke, must return false, so that the components of their own touching processing to retain.