Simple way to order an ArrayList in Java

Often in Java one ends up using ArrayLists to store objects.

Every now and then becomes needed to sort the elements inside an array, either in descending or ascending order according to some attribute of the object.

This is a somewhat tricky operation that gets forgotten too often, therefore I'm documenting it for future reference to myself. Much of what is written here was based on the tutorial from Mkyong: http://www.mkyong.com/java/java-object-sorting-example-comparable-and-comparator/


First step:
Make the object that you want to order to extend the "Comparable" class.

On my case, I want to apply the ordering on the SourceCodeObject class, so I add the line:
        implements Comparable<SourceCodeFile>

And it looks like this:
https://github.com/triplecheck/f2f/blob/26db102366be6b1eaeae2fcbb8bb0e966d951d6a/src/structure/SourceCodeFile.java#L25


Second step:
Override the "compareTo" method. On this case the comparison can occur between any two attributes of the objects that you are comparing. I find it difficult to understand in detail how it works. For my case it was enough to subtract two values and return the value. You find the code example at:
https://github.com/triplecheck/f2f/blob/26db102366be6b1eaeae2fcbb8bb0e966d951d6a/src/structure/SourceCodeFile.java#L150-L153


Third step:
Convert the ArrayList to an array and then sort the array. This is the part that I find tricky because the syntax to convert the ArrayList to a plain array is not straightforward to understand, even from the help menu.

It should be something like:
        SourceCodeFile[] array = myArrayList.toArray(new SourceCodeFile[myArrayList.size()]);
        Arrays.sort(array);



You find the code example at:
https://github.com/triplecheck/f2f/blob/26db102366be6b1eaeae2fcbb8bb0e966d951d6a/src/structure/AnalysisResult.java#L223-L225


That's it. Enjoy the sorted array!

In resume:
- Add the "Comparable" class to the object you want to compare
- Add the "toCompare" method
- Apply the Arrays.sort for ordering the items on a new array.


Simpler ways?
This method worked for me and I found it ok. Surely other ways exist. What do you think? How would you have implemented ordering?