Integer.valueOf () value

Question

Is there a reason to use Integer.valueOf (X) to initialize the final integer, as shown below:

public class MyClass
{
  public static final Integer DAY_1 = Integer.valueOf(1); // Why do it this way?
  public static final Integer DAY_2 = 2; // When it can be done this way?
}

I understand that this was necessary in older versions of Java before autoboxing was added. Is there a reason for this type of code? Or is it just a bad habit?

Answer 1

• There appeared a lot of code written before 1.5. There is no need to update it without any benefit.
• In some cases, it’s clear that you are boxing. In the case when you gave you, you can easily see the type of target in one line - but this is not always the case.
• , Integer int, Integer, .

Answer 2

, , DAY_1 (), int.

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Answer 3

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Answer 4

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Answer 5

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Answer 6

Integer.valueOf(1) ; -128 128 , , Integer (1) . , , (Integer, Long, BigDecimal ..), , , , autoboxing .

Bart van Heukelom, the difference between list.remove (1) and list.remove (new Integer (1)) is this; list.remove (1) will remove the object from index 1 from the list, list.remove (new Integer (1)) will remove all objects in the list that are equal to the Integer object with a value of one. Remember that collections cannot store primitives, only objects.

Answer 7

This is a bad habit, and there is no reason for this, as the compiler will generate Integer.valueOf()for you.