Java scope: Public, private, protected, and no-write differences

Before explaining the Four keywords, I want Class Make a simple definition of the relationship between them. Class , Base Class It can be thought that they are all their children, and Classes And think they are all friends of their own.

 

1,Public:PublicIndicates that the data member and member function are open to all users, and all users can directly call the function.

 

2,Private:PrivatePrivate means thatClassNo one except yourself can use it directly. Private property cannot be infringed. Even children and friends cannot use it.

 

3 , Protected : Protected For children and friends Public Can be used freely, without any restrictions, and for other external Class , Protected It becomes Private .

Scope: current class, same package, Child class, other package

Public √

Protected √ ×

Friendly √ ××

Private √ ×××

The default value is friendly when no data is written.