Will the compiler-generated default constructor be public?

问题

When I write a class Widget.java

public class Widget {
    int data;
    String name;
}

will the compiler-generated constructor be public or default?

public would be like

public class Widget {
    int data;
    String name;
    public Widget() {}
}

whereas default similar to

public class Widget {
    int data;
    String name;
    Widget() {}
}

回答1:

It depends on your class visibility.The compiler uses the class visibility and generates a no-arg default constructor with the same visibility

回答2:

As said in JLS

If a class contains no constructor declarations, then a default constructor that takes no parameters is automatically provided:

1. If the class is declared public, then the default constructor is implicitly given the access modifier public;
2. If the class is declared protected, then the default constructor is implicitly given the access modifier protected;
3. If the class is declared private, then the default constructor is implicitly given the access modifier private;
4. Otherwise, the default constructor has the default access implied by no access modifier

回答3:

As classes visibility is public, it will always be a public constructor.

回答4:

It will be public as the class visibility is public

public Widget() {}

回答5:

It will be public Widget() {}

回答6:

Depends on class visibility. For your class dafault constructor is going to be public.

In a class type, if the class is declared public, then the default constructor is implicitly given the access modifier public (§6.6); if the class is declared protected, then the default constructor is implicitly given the access modifier protected (§6.6); if the class is declared private, then the default constructor is implicitly given the access modifier private (§6.6); otherwise, the default constructor has the default access implied by no access modifier.

From here.

回答7:

If your class is public then the default constructor would be public so in your case, Since the Widget class is public its default constructor supplied by the compiler would also be public. See this

来源：https://stackoverflow.com/questions/21750609/will-the-compiler-generated-default-constructor-be-public