Develop Reference

How to understand this exception raised in an OpenCV program

I have got the following exception in my OpenCV program. I had the following image in my computer and I moved it to my mobile phone and read it by Mat imageRead = Highgui.imread("/mnt/sdcard/Pictures/2im00.png");
Then I tried to convert its color space to HSV using the following statement, and got the exception on this statement.
Imgproc.cvtColor(imageRead, hsvImage, Imgproc.COLOR_RGB2HSV);
But the exception does not seem to tell me anything more than that it is in the function cvtColor, or I can't read the encoded information there.
So the question is that how do I find out why I am getting this exception?
Is there any coded information there, like some codes (like scn==3 or scn==4 or error:-215 or depth etc etc), which I can browse somewhere to find out why I am getting the exception?

Most probably, Assertion failure occurs because you are passing an empty image to the cvtColor function.
Or
The Mat image you are passing is not an CV_8U or CV_32F format.
I agree with Miki's comment for more details follow this link How to interpret c++ opencv Assertion error messages due to an error in cvtColor function?

MEDIA_PROJECTION_SERVICE not valid in call to getSystemService()

I am trying to develop an application that requires the ability to capture screen content. I'm targeting lollipop to avoid the requirement for root. When trying to get an instance of the MediaProjectionManager via a call to getSystemService() I am getting the following error reported in Android Studio:
Must be one of: Context.POWER_SERVICE, Context.WINDOW_SERVICE, Context.LAYOUT_INFLATER_SERVICE, Context.ACCOUNT_SERVICE, Context.ACTIVITY_SERVICE, Context.ALARM_SERVICE, Context.NOTIFICATION_SERVICE, Context.ACCESSIBILITY_SERVICE, Context.CAPTIONING_SERVICE, Context.KEYGUARD_SERVICE, Context.LOCATION_SERVICE, Context.SEARCH_SERVICE, Context.SENSOR_SERVICE, Context.STORAGE_SERVICE, Context.WALLPAPER_SERVICE, Context.VIBRATOR_SERVICE, Context.CONNECTIVITY_SERVICE, Context.WIFI_SERVICE, Context.WIFI_P2P_SERVICE, Context.NSD_SERVICE, Context.AUDIO_SERVICE, Context.MEDIA_ROUTER_SERVICE, Context.TELEPHONY_SERVICE, Context.CLIPBOARD_SERVICE, Context.INPUT_METHOD_SERVICE, Context.TEXT_SERVICES_MANAGER_SERVICE, Context.DROPBOX_SERVICE, Context.DEVICE_POLICY_SERVICE, Context.UI_MODE_SERVICE, Context.DOWNLOAD_SERVICE, Context.NFC_SERVICE, Context.BLUETOOTH_SERVICE, Context.USB_SERVICE, Context.INPUT_SERVICE, Context.DISPLAY_SERVICE, Context.USER_SERVICE, Context.PRINT_SERVICE less... (Ctrl+F1)
Reports two types of problems:
* Supplying the wrong type of resource identifier. For example, when calling Resources.getString(int id), you should be passing R.string.something, not R.drawable.something.
* Passing the wrong constant to a method which expects one of a specific set of constants. For example, when calling View#setLayoutDirection, the parameter must be android.view.View.LAYOUT_DIRECTION_LTR or android.view.View.LAYOUT_DIRECTION_RTL.
I am currently at a loss as to why this constant is not considered valid, it's there as an autocomplete option, so it's present, and it's shown in all sample code I have seen for screen capture in lollipop. I have verified that the project setup specifies Android SDK 21 as min and target. Is there something else obvious/stupid I might be missing that would cause this error?
UPDATE: Took the exact same code to Eclipse and it works without issue. So this is related to something in Android Studio specifically it seems.

I get this error while getting Context.BLUETOOTH_SERVICEand the error doc (Must be one of..) contains Context.BLUETOOTH_SERVICE though.
This is not the way Android Studio "1.2" should work. :#
Anyway, its an Inspection bug, Constant and Resource Type mismatch (How in the hell Bluetooth is a resource in android context).
You can suppress this for Class/Method/Statement, for statement, add #SuppressWarnings("ResourceType") above or before the statement.
Another approach:
Goto Settings>>Editor>>Inspection>>Android>>Constant and Resource Type Mismatches and make the severity to anything but Error, probably Warning or Weak Warning.
(Though it fixes the error issue, but I want this mismatch to be an error when it really happens.)

Run into the same problem, it is so strange, there are no any other threads talking about this problem.
Well, actually you can just ignore this error and still run the program, even with
the red marks on it

MVEL2 on android throws exception

Did anyone has experience with MVEL2 on android?
i've tried out the same code with a simple java program and later on android:
The following exception is thrown when executed on android:
E/AndroidRuntime(30793): java.lang.ExceptionInInitializerError
I tried the example from the mvel website:
String template = "Hello, my name is #{name.toUpperCase()}";
Map vars = new HashMap();
vars.put("name", "Michael");
System.out.println(TemplateRuntime.eval(template, vars));
If theres no solution could anyone suggest a template engine which works with android
and supports iteration?

MVEL2 tries to substring the first 3 characters of the system java.version property when initializing the parser, and under Android the version is 0. That causes a bunch of exceptions which eventually cause the ExceptionInInitializerError.
If you want to force the java.version property, you can simply set it yourself:
System.setProperty("java.version", "1.6");
I have no idea what kind of odd side effects this may cause for Android, but at least it gets the MVEL parser up and running without throwing exceptions!

System.setProperty with "java.version" key seems to be read only propery in android, so it won't work.
i've tried to integrate MVEL 2 into android with no success, try using EVAL lib

Writing to log causes App to crash?

I was going through following tutorial: http://www.dreamincode.net/forums/topic/190013-creating-simple-file-chooser/#viewSource
Inside the FileChooser class there is one exception beeing supressed, since there is nothing within the catch clause. So I decided to add following statement to the catch clause:
Log.e(ACTIVITY_SERVICE, e.getCause().toString());
For some reason this always causes the app to crash (NullPointerException). When I don't do any logging, except for a a simple syso print, then I don't get any exception and the app does't crash either. Then it works fine. I'm new to the whole Android Framework and just want to understand why this is happening.

Thanks to Ingo's and CommonsWare's hints I came to the conclusion, that following line caused the exception:
EDIT:
In fact it was the start of the foreach loop, which iterates over all subdirectories and files of a given directory. I didn't know, that this would cause a NPE, if the list you want to iterate on is actually null. For some reason I thought that the loop would be automatically skipped in this case.

Why am I getting "can't find view" exceptions when the layout hasn't changed?

I'm working on one of my android widgets, which uses LauncherPlus to add scrolling functionality, and am running into a frustrating issue. My currently published version of the code, again using LauncherPlus, is working well, scrolling and all. I'm adding a requested feature, one which allows changing text sizes, but an exception is thrown when I test the update. There exception is:
mobi.intuitit.android.widget.SimpleRemoteViews$ActionException: can't find view:0x7f070041
I haven't changed anything in the layouts and the only code change references a view id which was already referenced in that same section of code. I looked through the R.java and found which resource was referred to and again, nothing has changed there. Here's the bit of code where the issue is coming from:
itemViews.setBoundBitmap(R.id.profile, "setImageBitmap", SonetProvider.SonetProviderColumns.profile.ordinal(), 0);
itemViews.setBoundCharSequence(R.id.friend, "setText", SonetProvider.SonetProviderColumns.friend.ordinal(), 0);
itemViews.setBoundCharSequence(R.id.created, "setText", SonetProvider.SonetProviderColumns.createdtext.ordinal(), 0);
itemViews.setBoundCharSequence(R.id.message, "setText", SonetProvider.SonetProviderColumns.message.ordinal(), 0);
The exception is thrown when applying the first line. Out of curiosity, I changed the order of these lines, and each one of them will cause the exception, though again, the layout hasn't changed. After the exception is thrown the widget will build successfully, but I can't publish this update with an exception (force close) being thrown. Any ideas why there is a resource issue? Thanks!
UPDATE:
I found this discussion where it seems that widget resources may not be reloaded on application updates:
http://groups.google.com/group/android-developers/browse_thread/thread/55a8e44974e8c6ad?fwc=1&pli=1
Does anyone have any experience with this, or a workaround? This may be what I'm facing.

Use Project > Clean in Eclipse or ant clean from the command line, then try again. Since resource IDs are integers, they are inlined in the bytecode of the classes that reference them, and so sometimes your pre-compiled classes can get out of sync with new resource IDs from a fresh compile. I work from the command line mostly, and I always tack clean onto my ant commands (e.g., ant clean install) to avoid this problem.