android基础(1)
/**以下内容主要来源于android-sdk-windows/docs**/

进程和线程
android的UI是非线程安全的，所以不能在工作线程中访问UI对象，两个简单的原则:
1.不要阻塞UI线程
2.不要在除UI线程外的线程中直接访问UI对象

在工作线程中访问UI对象的方法:
Activity.runOnUiThread(Runnable)View.post(Runnable)[url=http://developer.android.com/reference/android/view/View.html#postDelayed(java.lang.Runnable, long)]View.postDelayed(Runnable, long)[/url]

例子:

private class DownloadImageTask extends AsyncTask<String, Void, Bitmap> {      /** The system calls this to perform work in a worker thread and       * delivers it the parameters given to AsyncTask.execute() */      protected Bitmap doInBackground(String... urls) {          return loadImageFromNetwork(urls[0]);      }            /** The system calls this to perform work in the UI thread and delivers       * the result from doInBackground() */      protected void onPostExecute(Bitmap result) {          mImageView.setImageBitmap(result);      }  }    //在工作线程中调用  new DownloadImageTask().execute("http://example.com/image.png"); 

在services和content provider中的方法通常要线程安全