Returning an empty array

Question

I m trying to think of the best way to return an empty array  rather than null   Is there any difference between foo   and bar     private static File   foo         return Collections emptyList   toArray new File 0          private static File   bar         return new File 0

User · Answer

Definitely the second one  In the first one  you use a constant empty List lt   gt  and then convert it to a File    which requires to create an empty File 0  array  And that is what you do in the second one in one single step

User · Answer

A different way to return an empty array is to use a constant as all empty arrays of a given type are the same   private static final File   NO FILES       private static File   bar        return NO FILES

User · Answer

Both foo   and bar   may generate warnings in some IDEs  For example  IntelliJ IDEA will generate a Allocation of zero-length array warning   An alternative approach is to use Apache Commons Lang 3 ArrayUtils toArray   function with empty arguments   public File   bazz         return ArrayUtils toArray        This approach is both performance and IDE friendly  yet requires a 3rd party dependency  However  if you already have commons-lang3 in your classpath  you could even use statically-defined empty arrays for primitive types   public String   bazz         return ArrayUtils EMPTY STRING ARRAY

User · Answer

I m pretty sure you should go with bar    because with foo    it creates a List  for nothing  since you create a new File 0  in the end anyway  so why not go with directly returning it

User · Answer

return new File 0     This is better and efficient approach

User · Answer

There is no difference except the fact that foo performs 3 visible method calls to return empty array that is anyway created while bar   just creates this array and returns it

User · Answer

In a single line you could do   private static File   bar        return new File

User · Answer

You can return empty array by following two ways   If you want to return array of int then   Using      int arr         return arr   Using new int 0    int arr     new int 0   return arr     Same way you can return array for other datatypes as well

[java] Returning an empty array

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