What are the complete source codes of an App system?

A complete java source program should include the following parts:

Package statement; //There is only one sentence in this part at most, which must be placed in the first sentence of the source program.

Import declaration; /* There may or may not be several import statements in this section, and it must be placed before all class definitions */

Common class definition; //In the public classDefinition section, there is at most one public class definition. //java language stipulates that the file name of Java source program must be exactly the same as the common class name. Category definition; //In the class definition section, there can be 0 or more class definitions.

Interface definition; //In the interface definition section, there can be zero or more interface definitions. For example, a java source program can have the following structure, and the source program is named Hello World App. Java: Package Java Work. Hello world/* compile everything. Class files are put into the package javawork.helloworld */importjava.awt. *; //Tell the compiler that this program uses the AWT package importjavawork. newcentury of the system; /* Tell the compiler about the user-defined package javawork.newcentury*/

The definition of public class HelloWorldApp {...}/* The name of public class hello world app is the same as the file name */class First Class {...}//Definition of the first public class First Class Second Class {...}//Definition of other common class interfaces First interface {...}/* First interface.

Definition of the first interface */...//Other interface definitions