[android-developers] What does the "Application modularity" mean in android offical document?

hi,all there is an article in android document(Dev Guide/Publishing/Signing Your Applications/Signing Strategies) "Application modularity – The Android system allows applications that are signed by the same certificate to run in the same process, if the applications so requests, so

[android-developers] File permission about MediaPlayer

Code first: InputStream is = ;//some mixed audio byte buf[] = new byte[1024]; System.out.println(tempDir.getAbsolutePath()); File temp = File.createTempFile("aaa", ".mp3", this.getCacheDir()); FileOutputStream out =