1. Language background
The Java language is the father of the computer language Java launched by the US Sun Corporation (Stanford University Network) in 1995
: James Gosling (James Gosling) In
2009, Sun Corporation was acquired by Oracle Corporation, so we can now visit the Oracle official website: https ://www.oracle.com
2. version
Java is divided into three systems:
- JavaSE (J2SE) (Java2 Platform Standard Edition, Java Platform Standard Edition)
Develop common desktop and business applications, which are the basis for the other two categories
- JavaEE (J2EE) (Java 2 Platform, Enterprise Edition, Java Platform Enterprise Edition)
It is a set of solutions for developing applications in the enterprise environment, including Servlet, Jsp, etc., mainly for Web application development
- JavaME (J2ME) (Java 2 Platform Micro Edition, Java Platform Micro Edition).
is a solution for developing consumer electronics and embedded devices
3. Features (Baidu search)
Simple, object-oriented, distributed, etc., check Baidu
Baidu link: https://baike.baidu.com/item/Java/85979?fr=aladdin
4、jdk、jre、jvm
JDK (Java Development Kit) is called Java development tools, including JRE and development tools
JRE (Java Runtime Environment), Java runtime environment, including JVM and Java core class library (Java API)
JVM (Java Virtual Machine), Java Virtual machine
Summary: We only need to install JDK, which contains the java operating environment and virtual machine.
5. Java environment construction
Construction details: https://coderwcb.blog.csdn.net/article/details/127143366
6. Development and operation process
7. Java quick start
- Common commands for getting started
javac(java compiler): responsible for compilingjava: responsible for running
- write
.javaa document - compile code
javac xxx.java - Run the code
java xxxwithout class
8. Java cross-platform principle
The Java program is not run directly. The Java compiler compiles the Java source program into a platform-independent bytecode file (class file), and then the Java Virtual Machine (JVM) interprets and executes the bytecode file , that is, " compile first explaining ". Therefore, under different operating systems, you only need to install different Java virtual machines to realize cross-platform java programs. i.e. compile once, run everywhere