Java is an object-oriented programming language, and the language style of C++ is very close. It inherits the core of C++ object-oriented technology. Features such as pointers, operator overloading, and multiple inheritance have been discarded, and garbage collection has been added for memory management.
Second, the characteristics of java:
1. Platform independence: java can be executed on different operating systems. Java introduces the principle of virtual machine and executes it in virtual machine 2. Security: when the program is executed. Memory is allocated by the operating system. 3. Robustness: Java focuses on checking errors during compilation and execution of programs, which is conducive to finding errors in an early stage of development. In addition, certain verification functions are provided. 4. Dynamic: The basic unit of a java program is a class. The class is loaded dynamically during execution, and there is no need to change the program again after the class library is upgraded.
Three, java platform
The java platform consists of the java virtual machine and the java core classes. It provides a unified programming interface for java programs. Regardless of what the underlying operating system is. The java platform we are talking about now generally refers to java2, which includes three version numbers: 1. Standard Edition (J2SE): mainly used for programming of desktop applications 2. Enterprise Edition (J2EE): mainly used for distributed Development of web programs. 3. MicroEdition (J2ME): Mainly used for the development of embedded systems The relationship between the three is J2EE including J2SE. J2ME includes the core classes of J2SE. However, some new applications for proprietary classes have been added. On the whole, J2SE is the foundation. It is J2ME when it is compressed and some features such as CLDC are added. When it is expanded, it is said that J2EE is added with some enterprise application features such as EJB.
Fourth, the development process of java program
1. Write the source file (use a text editor to edit the text. Save the compiled source file, the source file extension must be .java) 2. Compile the source file (use the java compiler javac.exe to compile) 3. Execute java program
summary
Here is just a simple study and understanding of J2SE. J2SE is the foundation of Java, you should study it carefully and practice and experience it in the project.
