Comparing Performance of int and Integer

Question

Which one is best in programming - int or Integer? Especially whenever both are doing the same task?

I am writing an application in Java. In most of the places of primitive data types, I use int; and for objects, I use Integer. So I am confused- which one is the best in places, where we have to use objects.

According to performance, which one is best for a Java application?

Answer 1

Use int when possible, and use Integer when needed. Since int is a primitive, it will be faster. Modern JVMs know how to optimize Integers using auto-boxing, but if you're writing performance critical code, int is the way to go.

Take a look at this and this article. Although you shouldn't treat them as absolute truths, they do show that objects will be slower than their primitive counterparts.

So, use int whenever possible (I will repeat myself: if you're writing performance critical code). If a method requires an Integer, use that instead.

If you don't care about performance and want to do everything in an object oriented fashion, use Integer.

Answer 2

Use int wherever possible. Use Integer only if:

• You need a way to represent "no value" or "uninitialized". Integer can be null, an int always has an int value.
• You want to use collections like List (though you can use int externally and have autoboxing hide the fact that the collection internally stores Integer instances).
• You're using an API, framework or tool that requires you to use Integer or Object, or doesn't work with primitive types.
• You need to be able to synchronize on the object (very unlikely).