Why does the Boolean object have a public constructor in Java?

Question

Documentation for the constructor new Boolean(boolean value) in Java states:

Note: It is rarely appropriate to use this constructor. Unle

Answer 1

valueOf() only got added in Java 1.4, so it would appear that the constructors exist for backwards compatibility.

This ticket explains the reasons for not deprecating the constructors:

Due to the disruption deprecating an API can have, currently an API has to be "actively hazardous" to be deprecated, like Thread.stop. While the use this constructor is certainly ill-advised, it doesn't rise (or sink) to the standard of hazardousness to be deprecated in the JDK. In the future we may add a "denigration" facility to mark API elements that aren't quite so bad that they should be deprecated, but shouldn't be used in most cases. This constructor would be a good candidate for denigration.

I can't think of a realistic scenario where using Boolean constructors would be the best way to do something useful.

Answer 2

The reason it hasn't been deprecated is that Java maintains backwards compatibility to version 1.0

I can't think of a good reason to use the constructor.

Answer 3

Usually, you will want to use valueOf(boolean) or even the Boolean.TRUE / Boolean.FALSE constants directly.

But think of a scenario where you want to use a private Boolean variable as a monitor for synchronizing threads. There you will need to make sure you use your own instance and have full control of it.

Answer 4

Another, not necessarily good reason would probably be to simply keep it consistent with the other native wrappers.

Answer 5

As of Java 9, the Boolean(boolean) constructor >>is<< deprecated; see javadoc.

For those who care about the history, there was a longstanding bug that called for the deprecation of the constructor. It was formally proposed in JEP 277 along with a number of other deprecations.