Java object-oriented partial class (Access format)

First, the basic concept

　　1. An inner class is a class that is defined in a class. Class A requires direct access to the members of Class B, the class A can be defined into Class B, as the inner class of Class B exists.

　　2. An inner class can be a member of an external class and can be modified by a member modifier. (For example: Public private static)

　　3. A static inner class can be used as an external class.

　　4. Non-static inner classes allow only static constants to be defined, and other static members cannot be defined.

　　5. Access rules:
An inner class can directly access members in an external class because the inner class holds a reference to the external class. External class name. This
An external class needs to create an inner class object to access the inner class.

Second, the example code

1 //External class outer2 classOuter3 {4     Private Static intnum = 4;5     6     //Inner class inner_17     classinner_18     {9         Ten         voidShow1 () One         { ASystem.out.println ("Inner class inner_1, Show1" +num);//the inner class inner_1 can directly access members of the External class outer num -         } -     } the      -     //methods in the Outer class method access methods in the inner class inner_1 Show1 -      Public voidMethod () -     { +Inner_1 in =Newinner_1 (); - In.show1 (); +     } A      at     //static inner class inner_2 -     Static classinner_2 -     { -         voidShow2 () -         { -SYSTEM.OUT.PRINTLN ("Internal static class inner_2, Show2" +num); in         } -         Static voidshow3 () to         { +SYSTEM.OUT.PRINTLN ("Internal static class inner_2, SHOW3" +num); -         } the     } *      $     classinner_4Panax Notoginseng     { -         Static Final intCount = 5;//static constants defined in an inner class the         voidshow4 () +         { ASystem.out.println ("Inner class inner_4, show4" +count); the         } +     } - } $  $ classInnerclassdemo - { -      Public Static voidMain (string[] args) the     { -         //creates an external class object, accessing the inner class. WuyiOuter out =NewOuter (); the Out . Method (); -          Wu         //creates a non-static inner class object that can be accessed by other external programs by creating an external class object.  -outer.inner_1 I1 =NewOuter ().Newinner_1 (); About I1.show1 (); $          -         //creates a static inner class object and accesses non-static members.  -outer.inner_2 i2 =Newouter.inner_2 (); - I2.show2 (); A          +         //creates a static inner class object and accesses static members.  the Outer.Inner_2.show3 (); -Outer.inner_2 I4 =Newouter.inner_2 (); $ i4.show3 (); the          the         //creates a non-static inner class object and accesses a static variable.  theOuter.inner_4 i5 =NewOuter ().Newinner_4 (); the i5.show4 (); -     } in}

Third, the code to run

　　

Java object-oriented partial class (Access format)