01java Basic Notes

Computer composition: arithmetic, controller, memory, input (external device I/O Device)
Machine Language: Machine language, Assembly language, Advanced languages
Human-computer interaction: command line mode, graphical interface interaction mode
The Java language platform is divided into: j2se,j2me,j2ee, cross-platform principle, Virtual Machine cross-platform, A compilation run everywhere
environment variable Settings
notes, explanations, Bug fixes
The identifier, cannot use the keyword, cannot begin with the number, the class interface each initial capital letter, the package is all lowercase middle dot, method except the first word first letter all uppercase, the constant all letter all uppercase, the middle adds _
Base: Jvm,jre (jre+ class library), JDK (jre+ class Library +kit)

01.01_ Computer Basics (computer Overview) (learn)

• A: What is a computer? examples of computer applications in life
  • Computer (computer) full name: electronic computer, commonly known as Computers. It is a modern intelligent electronic device which can operate according to the program, automatically and high-speed processing massive DATA. A computer consisting of hardware and software that does not have any software installed is called bare metal. Common forms are desktop computers, laptops, mainframe computers, and so On.
  • Application examples
    • 1: Scientific calculation
    • 2. Data processing
    • 3. Automatic control
    • 4. Computer Aided design
    • 5. Artificial Intelligence
    • 6. Multimedia Applications
    • 7. Computer Network
    • ...

• B: What is hardware? examples of hardware

  • Computer hardware (computer Hardware) refers to a computer system consisting of electronic, mechanical and optoelectronic components, such as a variety of physical devices collectively. These physical devices constitute an organic whole to provide the material basis for the computer software operation according to the requirements of the system Structure.
  • Von. Neumann architecture

  • The hardware of a computer is divided into 5 components: an operator, a controller, a memory, an input device, and an output device.

    • The operators and controllers are the cores of the computer, collectively known as central processing units (processing Unit,cpu) or Processors. There are also some high-speed storage units inside the cpu, called Registers. Where the operator performs all arithmetic and logic operations, the controller is responsible for removing the instruction from the memory, decoding and issuing various control commands to the computer, while the Register provides the processing unit with the data required for Operation.
    • Memory is a memory part of a computer that is used to store programs and data involved in a Program. It is divided into internal memory and external Memory. The internal memory is used to store the program being executed and the data used, its cost is high, the capacity is small, but the speed is Fast. External memory can be used for long-term preservation of a large number of programs and data, low cost, large capacity, but slower.
    • Input devices and output devices are collectively referred to as external devices, referred to as peripheral or I/O devices, for human-computer interaction and Inter-machine Communication. Microcomputers commonly used in the input device has a keyboard, mouse, etc., the output device has a display, printer and so On.
• C: What is software? software classification and examples
  • Computer software (computer Software) is an essential thing in the process of using a computer, and computer software can make the computer complete certain 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 chat yy language minesweeper

01.02_ Computer Basics (software Development and computer language Overview) (learn)

• A: What is software
  • A collection of computer data and instructions organized in a specific order
• B: What is development
  • The process of making software
• C: What is software development
  • Build software with development tools and computer language
• D: What is computer language
  • A special language for communicating information between people and computers
• E: Classification of computer languages
  • Machine Language:
    • Machine language is a computer language that is expressed directly in binary code instruction, which is a string of code consisting of 0 and 1, they have a certain number of digits and are divided into segments, and the coding of each segment represents different meanings.
  • Assembly:
    • Assembly language is to use some special symbols to replace the machine language binary code, the computer can not directly identify, need to use a software to translate assembly language into machine Languages.
  • Advanced Language:
    • The source code is written in plain english, and the source code is translated by the compiler into a machine language that is directly recognized by the computer and then executed by the Computer.
    • High-level languages include C,c++,c#,java

01.03_ Computer Basics (man-machine Interaction) (understanding)

• A: two ways of human-computer interaction
  • A: Command line mode
    • You need to have a console, enter specific instructions, and let the computer do some Work. More trouble, need to record some COMMANDS.
  • B: Graphical interface mode
    • This method is simple and intuitive, the user is easy to accept, easy to Operate.

01.04_ Computer Basics (keyboard Function keys and shortcut Keys) (master)

• A: keyboard function keys
  • A:tab is the opposite of Shift+tab.
  • B:shift
  • C:ctrl
  • D:alt
  • E: space
  • F:enter
  • G:window
  • H: up or down key
  • I:PRTSC (printscreen) Screen
• B: keyboard shortcuts
  • A:ctrl+a Select All
  • B:ctrl+c replication
  • C:ctrl+v paste
  • D:ctrl+x Cut
  • E:ctrl+z Revocation
  • F:ctrl+s Save

01.05_ Computer Basics (how to open the DOS Console) (master)

• How do I open the DOS console under a:xp?
  • A: Start – Program – Attachments – command Prompt
  • B: Start – Run –cmd– carriage return
  • c:win+r–cmd– Enter
• How do I open the DOS console under b:win7?
  • A: Start – All Programs – Accessories – command Prompt
  • B: Start – Search for programs and files –cmd– enter
  • c:win+r–cmd– Enter
• How to open the DOS console under C:win8
  • A: Left mouse click Start – down arrow – command prompt
  • B: Right click Start – Search –cmd– Enter
  • C: Mouse right click Start – Run –cmd– carriage return
  • d:win+r–cmd– Enter

01.06_ Computer Basics (common DOS commands explained)

• A:d: Enter drive letter Toggle
• B:dir (directory): list files and folders in the current directory
• C:CD (change Directory) Changes the specified directory (enter the specified Directory)
• D:cd. : Back to the top level directory
• E:cd: go back to the root directory
• F:cls: (clear Screen) Clear
• G:exit: exit DOS command line (need to master on split line, understanding Below)
• /=========================================================
• MD (make directory): Create directory
• Rd (remove directory): Delete directory
• Del (delete): Delete files, delete a bunch of suffix names like files *.txt
• Notepad creating a file
• Delete a folder with content
  • Rd +/S folder name (asking whether to Delete)
  • Rd +/q +/s folder name (delete directly)

01.07_java Language Basics (java Language Overview) (learn)

• The history of A:java language
  • James Goslin James Gosling received a BS in computer Science from the University of Calgary in Canada in 1977, a PhD in computer science from Carnegie Mellon University in 1983, and worked at IBM after graduating to design Ibm's first generation workstation news system, but it was not appreciated. Later transferred to sun, 1990, and Patrick,naughton and Mike Sheridan and other people to cooperate "green plan", later developed a set of languages called "Oak", then renamed Java.
  • SUN (Stanford University network, Stanford University Internet Company)
• B:java language version
  • jdk 1.1.4 sparkler gem 1997-09-12
  • JDK 1.1.5 Pumpkin pumpkin 1997-12-13
  • JDK 1.1. 6 Abigail Abigail – woman name 1998-04-24
  • JDK 1.1.7 Brutus Brutus – Roman statesman and general 1998-09-28
  • JDK 1.1.8 Chelsea Chelsea – city name 19 99-04-08
  • J2SE 1.2 Playground stadium 1998-12-04
  • j2se 1.2.1 None none 1999-03-30
  • j2se 1.2.2 Crick ET cricket 1999-07-08
  • j2se 1.3 Kestrel American Red Falcon (sǔn) 2000-05-08
  • j2se 1.3.1 Ladybird Ladybug 2001-05-17
  • J2SE 1.4.0 Merlin Gray back Hayabusa 2002-02-13
  • j2se 1.4.1 Grasshopper grasshopper 2002-09-16
  • j2se 1.4.2 Mantis Mantis 2003-06-2 6
  • javase 5.0 (1.5.0) Tiger Tigers
  • javase 5.1 (1.5.1) dragonfly Dragonfly
  • javase 6.0 (1.6.0) Mustan G Mustang
  • javase 7.0 (1.7.0) Dolphin Dolphin
• C:java Language Platform
  • J2SE (Java 2 Platform standard Edition) Edition
    • is a solution for developing common desktop and business applications, which is the basis for a number of other desktop applications to be developed
  • J2ME (Java 2 Platform Micro Edition) mini Version
    • is a solution for developing electronic consumer products and embedded devices
  • EE (Java 2 Platform Enterprise Edition) Corporate Edition
    • is a set of solutions for developing applications in an enterprise environment, including technologies such as servlets, jsps, etc., primarily for Web application development
• D:java language Features
  • Simplicity of
  • Explanatory nature
  • Object oriented
  • Performance
  • Distributed processing
  • Multithreading
  • Robustness
  • Dynamic
  • Structurally neutral
  • Security
  • Open source
  • Cross-platform

01.08_java Language Basics (java language cross-platform principle) (master)

• A: What is Cross-platform
• B:java Language Cross-platform principle
  • Just install a Java Virtual machine (JVM Java Vm) on the operating system that needs to run the Java Application. The JVM is responsible for the operation of the Java program in the System.
• C:java language Cross-platform Illustration
  • Write once, Run anywhere! (one compile, Run Everywhere)

01.09_java Language Basics (overview of JRE and Jdk) (master)

• A: What is a JRE
  • Including Java virtual machines (JVM Java) and the core class libraries required by Java programs, If you want to run a well-developed Java program, you only need to install the JRE on your computer.
  • jre:jvm+ class Library.
• B: what is a JDK
  • The JDK is available to Java developers, which includes Java development tools and the Jre. So with the JDK installed, you don't have to install the JRE separately.
  • Development tools: compilation Tools (javac.exe) Packaging Tools (jar.exe), etc.
  • Development tools for Jdk:jre+java.
• C: Why the JDK contains a JRE
  • Why does the JDK include a jre?
    • After the development of the program, you need to run a look at the Effect.
• The role and relationship of D:JDK,JRE,JVM

01.10_java Language Basics (download and installation process diagrams for Jdk) (learn)

• Download of A:JDK
  • A: Official website http://www.oracle.com
  • B: Demo download Process
• Installation of B:JDK
  • A: Fool-type installation
    • Double-click the installer and then go all the way next (but not recommended)
  • B: Recommended way to install
    • The installation path does not have Chinese or special symbols such as Spaces.
    • All development related software is the best installation directory Unified.
      • Example: My JDK installation path
        • D:\develop\Java\jdk1.7.0_72
    • When prompted to install the jre, you can choose not to Install. Recommended or Installed.
  • C: Demo installation process
    • You can set up a folder on the D drive first develop
    • Then demonstrate the installation process
• C: Verify the installation is successful
  • A: Through the DOS command, switch to the JDK installation bin Directory.
    • D:\develop\Java\jdk1.7.0_72\bin
  • B: then enter Javac and Java separately, If some content is displayed correctly, the installation is Successful.

01.11_java Language Basics (directory Interpretation under JDK installation Path) (learn)

• A:bin directory: This directory is used to store some executable programs.
  • such as Javac.exe (java compiler), java.exe (java runtime tool), jar.exe (packaging Tool) and * javadoc.exe (document generation tool), etc.
• B:DB directory: The DB directory is a small database. Datebase
  • Starting with JDK 6.0, a new member, javadb, is referenced in java, a pure Java implementation, Open source database management System. This database is not only lightweight, but also supports all JDBC 4.0 specifications, when learning jdbc, No more need to install a database software, choose to use JAVADB directly.
• C:jre directory: "jre" is the abbreviation for Java Runtime environment, meaning Java program runtime Environment. This directory is the root of the Java runtime environment, which includes Java Virtual machines, runtime class packages, Java application initiators, and a bin directory, but does not include development tools in the development Environment.
• D:include Directory: because the JDK is implemented through C and C + +, you need to introduce some c-language header files at startup, which is used to store these header Files.
• E:lib directory: Lib is the abbreviation for the library, meaning the Java class library or library file, which is the archive package file used by the development Tool.
• F:src.zip file: Src.zip is a compressed file for the SRC folder, and the source code for the JDK core class is placed in src, which allows you to view the source code of the Java base class.

01.12_java language Basics (introduction to Java development Tools) (learn)

• A:notepad (microsoft OS comes With)
• b:editplus/notepad++
• C:eclipse
• D:myeclipse
  • Give us a brief introduction to these tools and then tell us the order in which we use Them.
  • Basic Class: First notepad, then editplus, then Eclipse.
  • Employment Classes: MyEclipse and Eclipse are Used.

01.13_java Language Foundation (helloworld case writing and Running) (master)

• A: Defining classes
• B: Write the Main method
• C: Write output statement
• D:java Program Development operation and working principle

• E: compiling and running the program

  class HelloWorld {    public static void main(String[] args) {        System.out.println("HelloWorld");    }}

01.14_java Language Basics (helloworld Case Faqs) (master)

• A: can't find the file (show them all, let the students see what is the Problem)
  • A: File name extension shadowing causes compilation to fail
  • B: The file name is wrong
• B: Word spelling problems (show them all, let the students see what is going On)
  • A:class written as Class
  • B:string writes string
  • C:system written system
  • D:main written Mian
• C: bracket matching problem (show me how the problem is.)
  • A: Remove the curly braces from the class body
  • B: Remove the curly brace from the method body
  • C: Cut out the curly brace of the output statement.
• D: Chinese and English problems (show them all, let the students see what is the Problem)
  • A: message: error: illegal character: \???? The format
  • Note: English characters are basically required in Java programming
    .

01.15_java Language Basics (written format of the Java language (conventional, conventions better than coding)) (master)

• 1, curly braces to align, and write in pairs
• 2, There is a space in front of the left curly brace
• 3, the left curly brace to indent, Tab
• 4. Blank line between method and program block makes the program look clear
• 5, add spaces between statements, such as for statement
• 6, plus spaces on both sides of the operator

01.16_java Language Foundation (path environment variable function and configuration method 1) (master) Specify the running path of the program

• A: issues that are prone to developing programs in the bin directory of the JDK
  • A: If there are too many files, it is inconvenient to manage
  • B: Delete the unwanted files that you have written, and may accidentally remove the tool from the JDK.
• B: How to solve the problem?
  • Notepad why a command like this can be executed under any path, configure the PATH environment variable
• C: How to configure
  • A:XP system
    • Right click on desktop computer → select Properties → select advanced tab → Click environment variables → find path→ in system variable double-click path→ to add the bin directory under the JDK installation directory to the leftmost and add a Semicolon.
  • B:WIN7/WIN8 system
    • Right click on desktop computer → select Properties → select advanced system settings → select advanced tab → Click environment variables → find path→ under System variables double-click path→ to add the bin directory under the JDK installation directory to the leftmost and add a Semicolon.
• Path is configured with an executable File. exe, which can be configured to access executable files under Path paths under different drive characters

01.17_java Language Foundation (path environment variable configuration 2) (master)

• A: Configure Java_home First
• B: Modify Path again
• C: finally, The path is a sequential relationship.

01.18_java Language Basics (the Role of CLASSPATH environment variables and their Configuration) (understanding)

• A: Why to configure Classpath
• Principle of B:classpath Configuration

• C: How to configure Classpath

• The difference between path and classpath

  • Path is configured with an executable File. exe, which can be configured to access executable files under Path paths under different drive characters
  • Classpath configuration Java class file, which is The. class file
    * Configuration Classpath Plus semicolon and no semicolon?
    * If you do not add semicolons only go to classpath path to find
    * If you add a semicolon, go to classpath first, and then look in the current path

01.19_java Language Foundation (editplus Development Program and compile Run) (learn)

• A: Configure shortcut key compilation run
• B: Remove Backup files
  Automatic compilation ctrl+1 in editplus, running ctrl+2
  Tools Menu/preferences/categories/tools/custom Tools
  
  

Do not save temporary files on save:

Change the format of the new Java file generation class code (E.G. "{" is shown below or on the Left)

Change the location of the "{}" in the process of writing the Code:

01.20_java Language Basics (overview of annotations and their Classification) (master)

• A: What is a comment

• B: Classification and explanation of notes

  • Documentation comments not at the moment, said the following explanation

• The role of annotations

  • A: explanation procedure
  • B: Help us Debug errors

01.21_java Language Basics (overview and use of Keywords) (master)

• A: What is a keyword
  • Words that are given a specific meaning by the Java language
• B: features of the keyword
  • The letters that make up the keywords are all lowercase
• C: Common Keywords
  • public static void class, etc.
• D: keyword Considerations
  • Goto and const exist as reserved words, not currently used, advanced notebooks like editplus, with special color tags for keywords, very intuitive

01.22_java Language Basics (overview and composition rules for Identifiers) (master)

• A: What is an identifier
  • Is the sequence of characters to use when naming classes, interfaces, methods, variables, etc.
• B: constituent rules of identifiers
  • English uppercase and lowercase letters
  • numeric characters
  • $ and _
• C: identifier Considerations
  • 1, cannot use keyword
  • 2, cannot start with a number

01.23_java Language Basics (common Naming conventions in Identifiers) (learn)

• See the name of the idea
• A: Package
  • Preferably the domain name upside down, requires all the letters lowercase, the middle with dot separated
• B: class or interface
  • If a word is capitalized in the first letter
  • If it is more than one word, capitalize the first letter of each word (hump Principle)
• C: method or variable
  • If it is a word all lowercase
  • If multiple words, capitalize from the first letter of the second word
• D: constant
  • If it is a word, all the letters are capitalized
  • If there are multiple words, all the words are capitalized, and the words are underlined to distinguish each word

01.24_DAY01 Summary

• Summarize today's knowledge points once Again.

From for Notes (Wiz)

01java Basic Notes