Java中的空花括号/括号是什么意思？

Question

Here is the whole source code:

http://zerioh.tripod.com/ressources/sockets.html

Here is the code I want to highlight:

Provider(){}

What does this line means? Thanks.

Answer 1

It means that there's nothing to execute in this Constructor. Usually Java provides this by default so writing down Provider(){} is not necessary.

The main difference between this one and the one that is provided by the compiler by default is that the access is restricted since it's not public.

Answer 2

它是一个具有默认辅助功能的构造函数。

Answer 3

The no-arg constructor is simply being defined instead of being undeclared. However, since the access level modifier "public" was left out, this means the no-arg constructor is defined using the default package.

This means that any classes outside the package will not be able to instantiate it. Only classes within the package can instantiate the Provider class.

Answer 4

It is default constructor which does nothing.

An object of this class can be created withing the package.