Should autoboxing be avoided in Java?

Question

There are instances where a method expects a primitive type double and you pass a Double object as a parameter.

Since the compiler unboxes

Answer 1

It's a design-choice and not trivially answered for every case.

There are several items that could influence your decision:

Advantages:

• Auto-boxing and auto-unboxing can make your code easier to read:

  Leaving out all the unnecessary .doubleValue() and Double.valueOf() reduces the visual noise and can make your code easier to read.

• Auto-boxing allows you to easily use collections of primitive values (such as a List, ...)

Disadvantages:

• excessive, unnecessary auto-boxing and auto-unboxing can hinder your performance.

  For example, if you have an API that returns a double and another API that expects a double, but you handle the value as a Double in between, then you're doing useless auto-boxing.

• auto-unboxing can introduce a NullPointerException where you don't expect it:

  public void frobnicate(Double d) {
    double result = d / 2;
    // ...
  }
  

• using collections of auto-boxed values uses a lot more memory than a comparable double[] for example.