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Refactoring Java

Refactoring a Method

A class called Group has a method called getUsers(). Below are three versions of that method.
Please drag and drop the versions such that the best is on top, the 2nd best beneath it, and the worst is at the bottom.
  • Before you finish ordering, you can press the Show Hint button to reveal how many of your answers are right/wrong without specifying which are in the right/wrong position. Remember, you can continue to order items after hitting this button.
  • After you finish ordering, you can press the Check Answers button to see author commentary, as well as a green border for items in the right position and a red border for items in the wrong position.
Place these in the correct order: 
  • 
public class Group {
	// Gets users sorted by the most recently registered user
	public List getUsers() {
		List users = new ArrayList();
    		if (!new File(persistencePath()).exists())
			return users;
    		File[] files = new File(persistencePath()).listFiles();        
		for (File file : files)
    		if (file.isDirectory())
    			users.add(new User(file.getName(), this));
    		Collections.sort(users, new User.UserComparatorByDescendingRegistration());
    		return users;
	}
}
    The comment at the top of this method is deodorant for code that does not quickly communicate what it does. You have to puzzle your way through the lines of code to figure out what it is doing. This is indeed the worst example of the method.
    (Reading...)
     
  • 
public class Group {
	public List getUsers() {
		List users = new ArrayList();
    		if (!userDirectoryExists())
			return users;
    		// Add found users to users collection
		File[] files = new File(persistencePath()).listFiles();
		for (File file : files)
			if (file.isDirectory())
		    	users.add(new User(file.getName(), this));
    		// sort by most recently registered users
		Collections.sort(users, new User.UserComparatorByDescendingRegistration());
    		return users;
	}
}
    This version uses comments to help clarify what the code does, instead of extracting code into well-named methods that communicate what each step of the method does.
    (Reading...)
     
  • 
public class Group {
	public List getUsersSortedByMostRecentlyRegistered() {
		List users = new ArrayList();
    		if (!userDirectoryExists())
			return users;
    		addFoundUsersTo(users);
    		sortByMostRecentlyRegistered(users);
    		return users;
	}
}
    This is indeed the best version. It is easy to understand how the method does its work, and there is no need for comments. Even the method name helps to communicate exactly what kind of data the method returns. This method is a great example of what self-documenting code can be.
    (Reading...)
       
(Reading...)
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