Java Modifiers

Java Modifiers 大体可以分为两类：

     1) Access modifiers : public, protected, default, private

     2) Non- Access modifiers : strictfp, final and abstract

        Below are the modifiers for key word class:
       1.public: The class can be used anywhere

       2.abstract: The class is an abstract class and no instance of it can be generated

       3.final: The class cannot be inherited

       4.strictfp(strict floating point): Make the floating-point arithmetic in the class evaluated strictly. This ensures the interoperability of the floating-point calculation.

 

The following table shows what Access Modifiers are appropriate for classes, nested classes, member variables, and methods:

  Class Nested class Method, or Member variable Interface Interface method signature publicprotected package (default) private

visible from anywhere	same as its class	same as its class	visible from anywhere	visible from anywhere
N/A	its class and its subclass	its class and its subclass, and from its package	N/A	N/A
only from its package	only from its package	only from its package	only from its package	N/A, default is public
N/A	only from its class	only from its class	N/A	N/A

If a class has public visibility, the class can be referenced by anywhere in the program. If a class has package visibility, the class can be referenced only in the package where the class is defined. If a class has private visibility, (it can happen only if the class is defined nested in an other class) the class can be accessed only in the outer class.

If a variable is defined in a public class and it has public visibility, the variable can be reference anywhere in the application through the class it is defined in. If a variable has package visibility, the variable can be referenced only in the same package through the class it is defined in. If a variable has private visibility, the variable can be accessed only in the class it is defined in.

If a method is defined in a public class and it has public visibility, the method can be called anywhere in the application through the class it is defined in. If a method has package visibility, the method can be called only in the same package through the class it is defined in. If a method has private visibility, the method can be called only in the class it is defined in.