1 Computer basics
1.1 Computer
Computer (Computer) full name: electronic computer, commonly known as computer. It is a modern intelligent electronic device that can run in accordance with the program and process data automatically and at high speed. Common forms are desktop computers and notebook computers. According to the scale, it is divided into microcomputers, minicomputers, mainframes, supercomputers (supercomputers), etc.
John von Neumann, the inventor of the computer. The computer is one of the most advanced scientific and technological inventions in the 20th century. It has had an extremely important impact on human production and social activities, and has developed rapidly with strong vitality. Its application field has expanded from the initial military scientific research application to various fields of society, and a huge computer industry has been formed, which has led to global technological progress, which has triggered profound social changes. Computers have spread throughout ordinary schools and enterprises. Institutions, entering the homes of ordinary people, have become an indispensable tool in the information society.
A computer is composed of a hardware system and a software system. A computer without any software is called a bare metal.
Computer applications have penetrated into all areas of society, are changing the way people work, study and live, and promote social development. What aspects?
1.2 Computer hardware system
A computer is composed of a hardware system and a software system. A computer without any software is called a bare metal.
Computer Hardware (Computer Hardware) refers to the general term for various physical devices composed of electronic, mechanical, and optoelectronic components in a computer system. These physical devices form an organic whole according to the requirements of the system structure to provide a material basis for the operation of computer software.
The computer hardware system is usually composed of multiple components such as CPU, motherboard, memory, power supply, main box, hard disk, sound card, graphics card, network card, keyboard, mouse, monitor and so on.
1.3 Computer software system
Computer Software is an indispensable thing in the process of using a computer. Computer software can enable the computer to perform specific functions in a predetermined order.
Computer software is divided into system software and application software according to its function
System software: DOS (Disk Operating System), Windows, Linux, Unix, Mac, Android, iOS
Application software: office QQ League of Legends King Glory
1.4 Software development
Software: A collection of computer data and instructions organized in a specific order
Development: The process of making
software Software development: Making software with the help of development tools and computer languages
1.5 Computer language
Language: Human expression various symbols to communicate, and facilitate communication and the exchange of information between people
computer language:
a special language to communicate information communication between people and computers
computer languages are also characters, symbols and so
common Computer languages such as C, C++, C#, JAVA
1.6 Human-computer interaction
The emergence of software has achieved better interaction between humans and computers. There are two main ways of interaction:
graphical interface: this method is simple and intuitive, easy for users to accept, and easy to operate.
Command line mode: A console is required to input specific instructions to let the computer complete some operations. More troublesome, some commands need to be recorded.
1.7 Introduction to keyboard function keys and shortcut keys
To get started with programming, the first thing you need to know is the keyboard. Do you know the following? If you don’t know, let’s start here!
Tab Shift Ctrl Alt Space Enter Window
Up and Down Left and Right
PrtSc(PrintScreen) Screenshot QQ Screenshot Ctrl+Alt+A
Ctrl+A Select all
Ctrl+C Copy
Ctrl+V Paste
Ctrl+X Cut
Ctrl+Z Undo
Ctrl+Y Undo
Ctrl+S Save...
1.8 Common DOS commands
It used to be a graphical interface to operate, now let’s try to operate calculations through commands!
Press the "Window+R" keys at the same time, enter "cmd" in the pop-up window, press Enter to enter the DOS window, and you can start practicing~
Note: After entering, the default is under the c drive, it is best not to use the operating system drive, you can switch the drive letter
2 Overview of Java language
2.1 The history of Java language development
James Gosling received a bachelor's degree in computer science from the University of Calgary, Canada in 1977, and a doctorate in computer science from Carnegie Mellon University in the United States in 1983. After graduation, he worked at IBM and designed the first-generation IBM workstation NeWS System, but not taken seriously. Later transferred to Sun, in 1990, cooperated with Patrick, Naughton, Mike Sheridan and others in the "Green Project", and later developed a language called "Oak", which was later renamed Java .
History of JDK (Java Development Kit)
1.0 - 1.1 - 1.2 - 1.3 - 1.4 - 1.5
5.0 - 6.0 - 7.0 - 8.0……
Sun launched in 1995
In 1991, James Gosling of Sun Company and others began to develop Oak language
In 1994, the Oak language was renamed Java
Received the first investment of 100 million yuan in 1996
In 1998, jdk1.2 was proposed and renamed to java2
Later launched jdk1.3 jdk1.4
In 2005, it was renamed jdk5.0, with substantial version improvements
In 2006, Sun announced that it would release Java as free software
Since March 2007, all developers around the world can modify the Java source code
Jdk6.0 was launched in 2007
In April 2009, Oracle acquired Sun for US$7.4 billion
Jdk7 was officially released by Oracle in July 2011
Java 8 was officially released in March 2014
2.2 Java language platform version
- J2SE/JAVASE-Standard Edition-Standard Edition / Basic Edition
Develop solutions provided by ordinary desktop and business applications. This technical system is the foundation of the other two and can complete the development of some desktop applications. - J2ME/JAVAME — Micro Edition — Micro Edition/Mobile Edition
is a solution for the development of mobile devices and embedded devices (electrical appliances, robots, set-top boxes...). - J2EE/JAVAEE—Enterprise Edition—Enterprise Edition/Business Edition
is a set of solutions for developing applications in an enterprise environment, mainly for enterprise-level application development.
2.3 Java language features
Simplicity, high performance, compilation, interpretation, distributed processing, robustness, security, object-oriented, open source, cross-platform
什么是跨平台性？
Applications written in the Java language can run on different system platforms. What is the principle?
The JAVA programs we write are source files with ".java" as the suffix. These files need to be compiled and turned into bytecode files with ".class" as the suffix, which will be run by the JVM (JAVA Virtual Machine).
Then we only need to install a JVM on the OS (operating system) that needs to run the java application program, and the JVM is responsible for the running of the Java program in the system. Different OS (operating system) has corresponding JVM, so only need to write a Java program, it can be executed on multiple different operating systems. In this way, the cross-platform nature of the Java program is realized. Also known as Java has good portability.
Note that JVM is a prerequisite for Java language to be cross-platform, but JVM itself is not cross-platform
Congratulations! Novice Xiaobai successfully concluded the first lecture, and then we are going to start to build the programming environment. The
next section of JAVA programming environment (JDK+Eclipse) click here