A, java Language Overview
1.1 java Language Overview
java language was introduced in 1995 by the American company sun, the father of java: James Gosling, the latest version is the 2018 release of java10 version.
The so-called programming language, computer language, a programming language that people can give orders to the computer, let the computer finish features people want.
java language mainly used in the field of Internet development program. Storage such as Lynx, Jingdong, logistics systems and back-end servers to handle large data query, data mining.
1.2 Computer Basics
① binary: it only contains 0 and 1, every 2 into 1, per each 1 or a 0, is called a bit. Inventor Leib Nice.
② Byte: byte is the smallest unit of computer storage. Bit (bit) bytes (byte) every eight one byte. 1 byte = 8 bit 100Mbps represents bit, 15MB / s represents the byte. Only 1024. The 1KB = 1024 byte
③ Common DOS command: MS = DOS (Microsoft Disk Operating System), a command prompt (cmd) analog DOS commands. Start Command Prompt, win + r cmd input Enter. (1) Switching letter: D: (2) into the folder: cd XXX (+ tab keys can be abbreviated) (3) return to the previous: cd .. (4) quick access: cd XXX \ XXX \ XXX \ ( 5) back to the root directory: cd \ (6) View catalog files: dir (7) clear the screen: cls (8) to exit the cmd window: exit
Two, java language development environment to build program
2.1 java virtual machine ----- jvm
①JVM: is all hypothetical computer running java program, that translator.
② Cross-platform: writing a java software can run on any operating system, known as cross-platform java language, there jvm implemented, the program runs on a jvm. jvm running in the operating system.
2.2 JRE和JDK
①jre: java runtime environment is the program, including jvm and the required core class libraries
②jdk: is a java program development tools, and development tools included jre
③ containment relationships: jdk> jre> jvm
2.3 jdk installation
Oracle official website to download: www.oracle.com. When installing the main installation location: Do not have Chinese and spaces. After the next like.
Configuration 2.4 environment variables
①JAVA_HOME
②classpath
③path Configuration
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