changing .start() to .executeCommand()
resolved the issue of user selecting the negative index
renaming displayAllEntries() to getDisplayAllEntries()
renaming filteredDisplayEntries to getFilterDisplayEntries() in TextBuddyList.java
added a method convertStringToInteger() to handle possible numberformatexception in deleteEntry()
Remove magic number -1, using the constant variable of INVALID_INTEGER_INPUT
Renaming removeCMDFromInput() to removeCmdFromInput(), in order to follow the recommended coding standard guidelines