trainClassifier should only calculate the meanFeatureVector for a StudentImageCollectionEvent if all features have been extracted for all StudentImages

[sladomic]

Description:

• Start the TrainingJobService
• The trainClassifier method should calculate all the meanFeatureVectors for all the StudentImageCollectionEvents

Expected Result:

• meanFeatureVector is calculated for a StudentImageCollectionEvent if the featureVectors have been extracted for all the corresponding StudentImages

Actual Result:

• meanFeatureVector is calculated even though not all featureVectors have been extracted, resulting in a NullPointerException

Log:

01-02 14:24:53.470 20010-20189/org.literacyapp E/AndroidRuntime: FATAL EXCEPTION: Thread-162
                                                                 Process: org.literacyapp, PID: 20010
                                                                 Theme: themes:{}
                                                                 java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String org.literacyapp.model.StudentImageFeature.getFeatureVector()' on a null object reference
                                                                     at org.literacyapp.authentication.thread.TrainingThread.trainClassifier(TrainingThread.java:239)
                                                                     at org.literacyapp.authentication.thread.TrainingThread.run(TrainingThread.java:71)