访问修饰符的访问范围及其使用原则

访问控制修饰符：
        
              访问控制修饰符主要用于控制类，类中的变量，类中的方法的访问权限；

            访问控制修饰符：public--公开级,private---私有级,protecte----受保护级,默认的--没有访问控制符修饰，向同一个包的类开放；
     .........................................................................................................................................
        .      访问级别     .       修饰符          .       同类    .       同包       .        子类        .        不同包              .
        .      公开的       .        public         .       ok      .        ok        .          ok        .         ok                 .
        .      受保护的     .        protected      .       ok      .        ok        .          ok        .                            .
        .      默认的       .        无修饰符       .       ok      .        ok        .                    .                            .
        .      私有的       .        private        .       ok      .                  .                    .                            .
      .........................................................................................................................................
             【成员变量，成员方法和构造方法可以处于上面4个访问级别中的任意一个】
              顶层类（不包括内部类）处于public,默认的访问级别；
               访问控制符只能修饰类，成员变量，成员方法，而不能修饰局部变量；

 

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              修饰符                 类                成员变量               成员方法                构造方法                     局部变量
         .............................................................................................................................................
                public              true                true                 true                     true                        false
          ............................................................................................................................................
               protected            false               true                 true                     true                        false
         .............................................................................................................................................      
               private              false               true                 true                    true                         false
         ............................................................................................................................................   
               默认的                true               true                 true                      true                       true
        .............................................................................................................................................     
               abstract             true                false                true                      true                      false
        .............................................................................................................................................
               final                true                 true                true                      false                      true
       ..............................................................................................................................................
               static               false                true                 true                      false                     true
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