Java Simple Backend Application

Project Goal

• Create a series of classes which can filter and sort a list of User Post objects.

Skills

• Writing Java code
• Unit testing for Java
• Introduction to Object Oriented
• Debugging in IntelliJ

Getting Started

• Clone the repository to a Dev location (for example C:\Dev\posting-sorting-grad-project)
• Install IntelliJ Community
• Create a new folder inside of the root folder (~\posting-sorting-grad-project) called out.
  • Note that this folder and all contents are ignored by git
• Open the root folder in IntelliJ
  • Notice that a folder called .idea has been created in your project, the contents of this folder have been marked as git ignored
• Setup the JDK (java software development kit) from the hint at the top of IntelliJ. The installation should come with JDK 11
• In the project explorer, right click the source folder and choose "Mark Directory as > Sources Root"
  • This should now show the Main and UserPost classes as java classes
• Run the application by clicking the play button or by going to "Run > Run 'Main'"
  • This may fail if it cannot find an out folder or if the language setting isn't compatible with the java SDK running
• Look at the Run window for a list of the example posts

Tasks

The following tasks are intended to be completed without the use of java streams

• Create a new class called AuthorPostSorter which implements the PostSorter interface. Write the implementation for its sort method which returns the list of user posts in order of author name alphabetically ascending
• To test the functionality we want to add JUnit as a testing framework. Although dependencies could be added directly as a packaged jar this isn't very portable. Instead, we need a little more help in the project structure so this is a good opportunity to convert the project to Maven.
  • By default Maven relies on a master pom which assumes that the java language is 5. To fix this we need to add a couple of extra settings the project's pom.xml. See pom_fragment.tst
• Once we have JUnit set up add unit tests to confirm the behaviour of your AuthorPostSorter (Hint: right click the name of the class in IntelliJ and click "generate > unit tests"). You should check that the method can sort user posts by author name without case sensitivity and that the method can cope with bad input - e.g. a null or empty input list.
  • For the remainder of this project you should include new unit tests in addition to every new method/change in behaviour added to classes
• The SortOrder enum has been included in the solution. Adjust the PostSorter interface so that the sort method can be sorted in ascending or descending order and edit the AuthorPostSorter and tests accordingly
• Write classes which each provide a method for sorting by:
  • Date submitted
  • Number of likes
  • Length of content in post
  • Author name extended - if a surname is provided, sort by surname, otherwise sort by first name.
• Write a new interface called PostFilter for classes that can filter an input list and return a reduced list. Write classes which can filter by:
  • Author
  • Keyword in post content
  • Posts made between certain dates
  • Only posts which have likes
• Write classes for combining filters using AND and OR, for example can filter to return only posts made in "2019" or by someone named "Amy"
  • Hint: many Scott Logic interviewers can help with this task...
• Write new classes which leverage multiple sort/filters:
  • Name and then date posted
  • Keyword - Given a keyword return the posts ordered by the number of times the keyword appears in the Post content
• Write a new class which will extract topics from Post content using regex or otherwise (unit tests should be agnostic to the implementation here). Here we are considering a topic as a keyword that is used multiple times.
  • Write a method to group user posts into a topic and return the list sorted by supposed topics
• Write an over-arching UserPostService which exposes the various methods for sorting and filtering using the classes above.

Extension Tasks

• Rewrite the above sort and filter classes using java streams. All unit tests should be unaffected
• Write a class which can take a JSON representation of a filter and sort method and produce the runtime filter/sort for this