Java basics 1: Java Basics

Java basics 1: Java Basics
1 Computer Basics 1.1 What is software?

• Software: a collection of computer data and commands organized in a specific order.
• Common Software:
  • System software:
    • Such as DOS, Windows, and Linux.
  • Application Software:
    • Such as QQ and office

 

1.2 What is software development?

• Production Software

 

1.3 Human-Computer Interaction

• The emergence of software enables better interaction between people and examination papers.
• Interaction Mode:
  • Graphical interface: This method is simple, intuitive, and easy to use.
  • Command Line Mode: You need a console to enter specific commands for the computer to complete some operations, which is more troublesome. Remember some commands.

 

1.4 computer language

• Language: communication between people.
  • For example, Chinese people communicate with Chinese people, while Chinese people communicate with Koreans, they need to learn Korean.
• Computer Language: communication between people and computers.
  • If people want to communicate with computers, they need to learn computer languages.
  • There are many computer languages, such as C and java.

 

2 java language Overview

• Sun is a high-level programming language launched in 1995.
• Is an Internet-oriented programming language.
• As java technology continues to mature in the web field, it has become the preferred development language for web applications.
• Easy to learn, completely object-oriented, secure and reliable, and platform-independent programming languages.

 

2.1 three technical architectures of java

• J2EE: Enterprise Edition
  • Is a set of solutions for developing applications in an enterprise environment.
  • The technologies included in this technology system, such as Servlet and JSP, are mainly used for web application development.
• J2SE: Standard Edition
  • Is a solution for developing common desktop and business applications.
  • This technology system is the basis of other two technologies and can be used to develop some desktop applications.
• J2-small version
  • Is a solution for developing electronic consumption products and embedded devices.
  • This technology system is mainly used for small electronic consumer products, such as applications in mobile phones.

 

• After java5.0, It is renamed JavaEE, JavaSE, and JavaME.

 

2.2 features of the java language (cross-platform)

 

• With JVM (Virtual Machine), the same java program can be executed in three different operating systems. This achieves the cross-platform java program, also known as java, with good portability.

 

2.3 java environment build 2.3.1 clarify what is JRE and JDK

• JDK: java Development Kit
  • JDK is provided for java developers, including java development tools and JRE. Therefore, after JDK is installed, you do not need to install JRE separately.
  • The development tools are as follows:
    • Compilation tool: javac.exe
    • Packaging tool: jar.exe
• JRE: java Runtime Environment
  • Including the core class libraries required by java virtual machines and java programs. To run a developed java program, you only need to install JRE on the computer.

 

• In short: Use JDK to develop java programs and then let JRE run java programs.

 

2.3.2 download JDK

• Http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html

 

2.3.3 install JDK

• On Windows, go to the next step.

 

2.3.4 configure Environment Variables

• Configure JAVA_HOME

• Configure path

 

 

2.3.5 verify whether the verification is successful

 

3 first java program

Package java001;/*** first java program */public class HelloWorld {public static void main (String [] args) {System. out. print ("Hello, world! ");}}