Private Constructor? Why I would want one?

I know there are three ways to declare a Java constructor, such as public, protected and private, but why I would want private one?

Thanks in advance...

André AS
São Paulo - Brazil

André Asantos wrote:I know there are three ways to declare a Java constructor, such as public, protected and private, but why I would want private one?

Thanks in advance...

André AS
São Paulo - Brazil

when we don't want to create object from out side of the class, in this way we can provide security to our class.
There could be several situations when you want to make a constructor privates such as:

class contains static utility methods only.

A singleton behavior required.

Hope this helps

Minhaj

PS: take a look here for singleton details

André Asantos wrote:but why I would want private one?

When you dont want to create an instance of a class using its that particular constructor.

A side effect of making (all) the constructors private is that the class can't be sub-classed. This is because the constructor in the sub-class can't "see" a super class constructor.

André Asantos wrote:I know there are three ways to declare a Java constructor, such as public, protected and private, but why I would want private one?

Thanks in advance...

André AS
São Paulo - Brazil

One more example is a 'Constants' class. I usually use a Constants class to maintain public static final constants that will not change. I do not want this class to be instantiated since it would not make sense sub classing this class.

I really loved all helps...

André AS
São Paulo - Brazil