Why do people still use primitive types in Java?

Question

Since Java 5, we\'ve had boxing/unboxing of primitive types so that int is wrapped to be java.lang.Integer, and so and and so forth.

I see

Answer 1

Primitive types are much faster:

int i;
i++;

Integer (all Numbers and also a String) is an immutable type: once created it can not be changed. If i was Integer, than i++ would create a new Integer object - much more expensive in terms of memory and processor.

Answer 2

I can't believe no one has mentioned what I think is the most important reason: "int" is so, so much easier to type than "Integer". I think people underestimate the importance of a concise syntax. Performance isn't really a reason to avoid them because most of the time when one is using numbers is in loop indexes, and incrementing and comparing those costs nothing in any non-trivial loop (whether you're using int or Integer).

The other given reason was that you can get NPEs but that's extremely easy to avoid with boxed types (and it is guaranteed to be avoided as long as you always initialize them to non-null values).

The other reason was that (new Long(1000))==(new Long(1000)) is false, but that's just another way of saying that ".equals" has no syntactic support for boxed types (unlike the operators <, >, =, etc), so we come back to the "simpler syntax" reason.

I think Steve Yegge's non-primitive loop example illustrates my point very well: http://sites.google.com/site/steveyegge2/language-trickery-and-ejb

Think about this: how often do you use function types in languages that have good syntax for them (like any functional language, python, ruby, and even C) compared to java where you have to simulate them using interfaces such as Runnable and Callable and nameless classes.

Answer 3

Boxed types have poorer performance and require more memory.

Answer 4

Can you really imagine a

  for (int i=0; i<10000; i++) {
      do something
  }

loop with java.lang.Integer instead? A java.lang.Integer is immutable, so each increment round the loop would create a new java object on the heap, rather than just increment the int on the stack with a single JVM instruction. The performance would be diabolical.

I would really disagree that it's much mode convenient to use java.lang.Integer than int. On the contrary. Autoboxing means that you can use int where you would otherwise be forced to use Integer, and the java compiler takes care of inserting the code to create the new Integer object for you. Autoboxing is all about allowing you to use an int where an Integer is expected, with the compiler inserting the relevant object construction. It in no way removes or reduces the need for the int in the first place. With autoboxing you get the best of both worlds. You get an Integer created for you automatically when you need a heap based java object, and you get the speed and efficiency of an int when you are just doing arithmetic and local calculations.

Answer 5

The primitive types are much faster and require much less memory. Therefore, we might want to prefer using them.

On the other hand, current Java language specification doesn’t allow usage of primitive types in the parameterized types (generics), in the Java collections or the Reflection API.

When our application needs collections with a big number of elements, we should consider using arrays with as more “economical” type as possible.

*For detailed info see the source: https://www.baeldung.com/java-primitives-vs-objects

Answer 6

Objects are much more heavyweight than primitive types, so primitive types are much more efficient than instances of wrapper classes.

Primitive types are very simple: for example an int is 32 bits and takes up exactly 32 bits in memory, and can be manipulated directly. An Integer object is a complete object, which (like any object) has to be stored on the heap, and can only be accessed via a reference (pointer) to it. It most likely also takes up more than 32 bits (4 bytes) of memory.

That said, the fact that Java has a distinction between primitive and non-primitive types is also a sign of age of the Java programming language. Newer programming languages don't have this distinction; the compiler of such a language is smart enough to figure out by itself if you're using simple values or more complex objects.

For example, in Scala there are no primitive types; there is a class Int for integers, and an Int is a real object (that you can methods on etc.). When the compiler compiles your code, it uses primitive ints behind the scenes, so using an Int is just as efficient as using a primitive int in Java.