java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.io.File.getCanonicalPath()' on a null object reference
   at android.support.v4.content.FileProvider$SimplePathStrategy.getUriForFile(FileProvider.java:695)
   at android.support.v4.content.FileProvider.getUriForFile(FileProvider.java:400)
   at com.zeyi.up.UpdateManager.installApk(UpdateManager.java:309)
   at com.zeyi.up.UpdateManager.access$700(UpdateManager.java:37)
   at com.zeyi.up.UpdateManager$6.handleMessage(UpdateManager.java:293)
   at android.os.Handler.dispatchMessage(Handler.java:102)
   at android.os.Looper.loop(Looper.java:160)
   at android.app.ActivityThread.main(ActivityThread.java:6200)
   at java.lang.reflect.Method.invoke(Native Method)
   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:874)
   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:764)