Imagine youre a financial institution. Youve built an application that processes financial transactions, and there are a number of flags that need to be set as constants to determine application behavior.

You might choose to write code like this:

  public static final boolean CreateNewReferenceFolderAndFiles = true;

But then your boss would say, Bro, do you even object-orient? before firing you, because that isnt enterprise-y.

Skyfyre sent us this excerpt, from a four-million line application, which is definitely very enterprise-y.

First, you need to define several classes, and since this is Java, each of them must be in its own file:

  public abstract class ArchiveCreateNewReferenceFolderAndFiles
  {
  }

  public class ArchiveCreateNewReferenceFolderAndFilesTrue extends ArchiveCreateNewReferenceFolderAndFilesAbstract
  {
  }

  public class ArchiveCreateNewReferenceFolderAndFilesFalse extends ArchiveCreateNewReferenceFolderAndFilesAbstract
  {
  }

Then, youve got to create your actual constants:

public static final ArchiveCreateNewReferenceFolderAndFilesAbstract ARCHIVE_CreateNewReferenceFolderAndFiles_TRUE = new ArchiveCreateNewReferenceFolderAndFilesTrue();
public static final ArchiveCreateNewReferenceFolderAndFilesAbstract ARCHIVE_CreateNewReferenceFolderAndFiles_FALSE = new ArchiveCreateNewReferenceFolderAndFilesFalse();
/// later…
public static final ArchiveCreateNewReferenceFolderAndFilesAbstract archiveCreateNewReferenceFile = ARCHIVE_CreateNewReferenceFolderAndFiles_TRUE;

Now, youre ready to write some real conditionals based on flags:

  if(archiveCreateNewReferenceFile instanceof ArchiveCreateNewReferenceFolderAndFilesTrue) {
    //do stuff…
  }

Its simplicity itself, and just think about how maintainable it is. When you finally need to support FileNotFound, you simply need to inherit from the ArchiveCreateNewReferenceFolderAndFiles class to produce ArchiveCreateNewReferenceFolderAndFilesFileNotFound. Think of the extensibility! Think of the readability!

http://thedailywtf.com/articles/constantly-extended