1.JAVA Basic review--computer Foundation and environment variable configuration

Understanding of software development

Software development:

Software: A collection of computer data and instructions that follow a specific organization.

Development: Production software.

Program: A collection of ORDERED commands.

Interactive

There are two ways of human-computer Interaction: graphical interface and command line mode.

Graphical interface: Simple, intuitive and easy to operate.

Command line mode: Requires a console to understand some specific instructions, more cumbersome.

Computer language

Language: It is a way of communication between people.

Computer language: The way people communicate with computers.

Java language Overview

A language introduced by Sun Company in 1995.

Features: Simple and easy to learn, fully object-oriented, cross-platform.

Java three major editions

J2SE: Standard Edition, which is the foundation and core of the Java language, is also the foundation of the EE and J2ME Technologies, primarily for the development of desktop applications.

Java EE: Enterprise Edition, which provides a complete solution for enterprise application development, is mainly used in the development of Web programs, and is one of the most widely used areas in the field of application.

J2ME: Miniature version, mainly used for embedded development, development of mobile programs.

Note: The Java 5.0 version was renamed Java SE, Java EE, and Java ME.

Java Virtual machine

A Java Virtual machine abbreviation JVM, a tool used to parse programs written by Java, is a bridge between the program and the Platform (operating system).

The principle of the Java language cross-platform

Cross-platform implementation by installing different versions of the JVM on different platforms (operating systems) to resolve Java programs.

Java environment variable Building

The Jre:java runtime environment, which contains the core class libraries required by the JVM and Java programs, is used to run Java programs.

JDK (contains JRE): Jre+java Development tools: Compilers, packaging tools, etc.

Simple overview: Use the JDK development completion program to run the JRE.

Configuration of Java Environment variables

The environment variables that Java needs to configure are:

The main configuration of the Path:java environment variable, in order to be able to compile the source files anywhere.

Java_home: In order to change the JDK path, do not affect the path variable separately for the JDK to create a new variable, to prevent the misuse of other system variables.

Class_path: When you execute a class file, look for the scope of the class file's location, and the purpose of classpath is to tell the Java execution Environment which directories can find the classes or packages you need to execute the Java program.

1. Download and install the JDK

2. Right-click Computer--"attribute--" Advanced Configuration--"Environment variable-" system variable

3. Create a new java_home variable to copy the JDK installation path to the Java_home variable, and the path variable will not be affected when you change the JDK path.

4. Locate the system variable path for editing, and add%java_home%\bin to the front ; A path that is used to separate from other system variables (%: used to refer to a system variable, where the value of Java_home is referenced).

5. Create a new Class_path variable .; %java_home%\lib;%java_home%\lib\tools.jar;

Verify that the Java environment variable configuration is successful

Open Console input Javac display the following interface indicates a successful configuration

　　

　　

1.JAVA Basic review--computer Foundation and environment variable configuration