Code cleanup and minor bug fixes

[SarahKurek]

• [x] check for TODOs
• [x] sortFunction access modifier -> first private -> protected -> public
• [x] fix Java Code Warnings; Android Warnings & Typos are ignored due to limited time (warnings mainly because of typos, icons and spelling errors)
• [x] fix headers everywhere
• [x] consistent Button names -> btn
• [x] in on create view in Fragments consistent code structure
• [x] consistent header for notes and add book with ISBN typing.
• [x] consistent enums
• [x] using model instead of DAO: in BookOnlineFragment, BookBarcodeScanner and ImportBibTex?
• [x] either lamda function or new on click listener
• [x] check for unused code
• [x] check for deprecated functions: 3 deprecated functions which will be ignored due to limited time
• [x] check for unused imports
• [x] error handling (remove System.out.println, ...)
• [x] requireActivity instead of getActivity where possible in all Fragments
• [x] requireContext instead of getContext where possible in all Fragments
• [x] renaming the classes
• [x] consistent comments?
• [x] optimize context and view usage
• [x] create getter and setter for public members in Main Activity
• [x] assert bundle != null if missing -> because it is faster; we are aware that it is not consistent with other parts of our code

[claudia3]

Code Cleanup Checklist Classes

• [x] ApiReader
• [x] AsDefaultAppFragment
• [x] Author
• [x] AuthorDao
• [x] AuthorFormFragment
• [x] AuthorFragment
• [x] AuthorItem
• [x] AuthorRecyclerViewAdapter
• [x] AuthorRetriever
• [x] BackStackFragment
• [x] BibTexKeys
• [x] Book
• [ ] BookBarcodeScannerFragment
• [x] BookDao
• [x] BookFormFragment
• [x] BookFragment
• [x] BookItem
• [x] BookModel
• [x] BookNotesView
• [x] BookNotesViewModel
• [x] BookOnlineFragment
• [x] BookRecyclerViewAdapter
• [x] DatabaseHelper
• [x] DataValidation
• [x] DateConverter: one German String " Uhr" in static method
• [x] ExportBibTex
• [x] HelpFragment
• [x] HomeFragment
• [x] ImportBibTex

• [x] ImprintFragment

  Methods of interfaces are different (not all methods are in there e.g. compare InterfaceNoteDao with all other Dao Interfaces) -> will be dismissed due to limited time

• [x] InterfaceAuthorDao
• [x] InterfaceBookDao
• [x] InterfaceNoteDao
• [x] InterfaceShelfDao

• [x] InterfaceTagDao

• [x] IsbnRetriever
• [x] LibraryFormFragment
• [x] LibraryFragment
• [x] LibraryItem
• [x] LibraryKeys
• [x] LibraryModel
• [x] LibraryRecyclerViewAdapter
• [x] MainActivity
• [x] Note
• [x] NoteAudioItem
• [x] NoteDao: id in create() is not set. In other Dao classes it is set.
• [x] NoteItem
• [x] NoteModel
• [x] NoteRecyclerViewAdapter
• [x] NotesFragment
• [x] NoteTextItem
• [x] NoteTypeLut
• [x] RichTextEditor
• [x] RichTextEditorBulletSpan
• [x] RichTextEditorPart
• [x] RichTextEditorQuoteSpan
• [x] SearchFragment
• [x] SearchItem
• [x] SearchItemType
• [x] SearchModel
• [x] SearchRecyclerViewAdapter
• [x] SeekBarListener
• [x] Shelf: createDate is is left as a member variable for future use.
• [x] ShelfDao
• [x] ShelfItem
• [x] SortableItem
• [x] SortCriteria
• [x] SortDate
• [x] SortDialog
• [x] SortName
• [x] StorageKeys
• [x] Tag: Can be used in the future by others.
• [x] TagDao: Can be used in the future by others.
• [x] TextNoteEditorFragment
• [x] UriUtils
• [x] UriUtilsKeys
• [x] VoiceNoteEditorFragment