JAVA (2) of the class about access control

• Four access rights of the members of the class
  • private
    • In the current class can only access
  • No modification
    • The same class package can access
  • protected
    • The same package can access the class
    • Subclasses can be accessed in different packages
  • public
    • All classes can access
• Sample Code
  • The same package
    • 　

      . 1  Package com.study.main;
       // package with non-child class 
      
      . 3  public  class Two
       . 4  {
       . 5      Private  int A;
       . 6      protected  int B;
       . 7      public  int C;
       . 8       int D;
       . 9 }

       

    • 　

      Package com.study.main;
       // same bun class 
      public  class Son the extends the Main 
      { 
      
      }
      
      

       

    •  1 package com.study.main;
       2 //测试类
       3 import com.study.one.One;
       4 import com.study.one.SonOne;
       5 
       6 public class Main
       7 {
       8     private int a;
       9     protected int b;
      10     public int c;
      11     int d;
      12 
      13     public static void main(String[] args)
      14     {
      15         Main m = new Main();// same class 
      16          System.out.println ( "same class" );
       . 17          System.out.println (mA); // Private 
      18 is          System.out.println (MB); // protected 
      . 19          System.out.println ( MC); // public 
      20 is          System.out.println (MD); // no modification 
      21 is          
      22 is          son = S new new son (); // subclasses in the same package 
      23 is          System.out.println ( "the same package subclass " );
       24-  //         System.out.println (SA); // Private inaccessible 
      25         System.out.println (SB); // protected 
      26 is          System.out.println (SC); // public 
      27          System.out.println (SD); // unmodified 
      28          
      29          Two T = new new Two (); / / same class Feizi package 
      30          System.out.println ( "non-child class in the same package" );
       31 is  //         System.out.println (TA); // Private inaccessible 
      32          System.out.println ( TB); // protected 
      33 is          System.out.println (TC); // public 
      34 is          System.out.println (TD);// No Modifier 
      35          
      36          Sonone = SO new new Sonone (); // subclasses different packages 
      37 [          System.out.println ( "subclasses different packages" );
       38 is  //         System.out.println (SO. A); // Private inaccessible 
      39          System.out.println (so.b); // protected 
      40          System.out.println (so.c); // public
       41 is  //         System.out.println (so.d ); // no modification was unable to access 
      42 is          
      43 is          
      44 is          One = O new new One (); // different packages of non-child class 
      45         System.out.println ( "non-child class in a different package" );
       46 is  //         System.out.println (OA); // Private unable to access
       47  //         System.out.println (OB); // protected not access 
      48          System.out.println (OC); // public
       49  //         System.out.println (OD); // unmodified inaccessible 
      50          
      51 is          
      52 is      }
       53 }

       

  • Different packages
    • 　　

      Package com.study.one;
       // different packet classes Feizi 
      public  class One 
      { 
          Private  int A;
           protected  int B;
           public  int C;
            int D; 
      }

       

    • . 1  Package com.study.one;
       2  // different classes buns 
      . 3  Import com.study.main.Main;
       . 4  
      . 5  public  class Sonone the extends the Main
       . 6  {
       . 7  
      . 8 }

       

  • Run shot
    • 
      　　
• to sum up
  • The current class can access
  • A package of the same class can not access the private addition
  • Different subclasses package can access only public and protected
  • Different packages of non-child class can access only public

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