Java int to String - Integer.toString(i) vs new Integer(i).toString()

java string int
marcolopes picture marcolopes · Oct 14, 2010 · Viewed 1.2M times · Source

Sometimes java puzzles me.
I have a huge amount of int initializations to make.

What's the real difference?

  1. Integer.toString(i)
  2. new Integer(i).toString()

Answer

Jean picture Jean · Oct 14, 2010

Integer.toString calls the static method in the class Integer. It does not need an instance of Integer.

If you call new Integer(i) you create an instance of type Integer, which is a full Java object encapsulating the value of your int. Then you call the toString method on it to ask it to return a string representation of itself.

If all you want is to print an int, you'd use the first one because it's lighter, faster and doesn't use extra memory (aside from the returned string).

If you want an object representing an integer value—to put it inside a collection for example—you'd use the second one, since it gives you a full-fledged object to do all sort of things that you cannot do with a bare int.

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