01 Computer and Java Fundamentals (entry level)

Learning suggestions:

Take notes, add notes, write a summary
Don't rely entirely on books and videos
Establish an effective learning method
A shortcut to learning software programming-knocking, knocking
Practice Typing (Jinshan typing pass)

Main content:

Basic Computer knowledge
Java language Overview
JDK Download, install
HelloWorld case
Configuration of environment variables

1: Computer Overview (Learn)
(1) Computer
(2) Computer hardware
(3) Computer software
System software: Window,linux,mac
Application software: Qq,yy, Fei Qiu
(4) Software development (understanding)
Software: It consists of data and instructions. Calculator
Development: The software is done.
How to implement software development?
is to use development tools and computer language to make things
(5) language
Natural language: The communication between people and people
Computer language: The communication between man and computer
C,c++,c#,java
(6) Man-Machine Exchange
Graphical interface: Easy to operate
DOS command: Need to memorize some common commands

2: Understanding of Keyboard function keys and shortcut keys (master)

(1) Understanding of function keys

TAB Shift CTRL ALT WinDOS space up or down enter enter PrtSc (printscreen)

(2) Shortcut keys

Select All Ctrl + a copy Ctrl + V Paste Ctrl + v.

Cut ctrl+x Undo Ctrl + Z save Ctrl+s

3: Common DOS commands (master)

Open DOS window must be (three kinds)

①window (Key) +r

② press SHIFT + right mouse button "Windows 7" in the Blank space of the desktop

③ mouse click on the lower left corner of the icon, in the Run window input cmd

(1) The following are common

Switch letter of the drive letter:

switch of the drive letter D: Enter

Entry of the catalogue

Single-stage access to CD folder
Multilevel access to CD folder \ folder \ Folder ...

Fallback for Directory

Single-level fallback CD:
Multi-level fallback cd\

Clear Screen CLS

Exit exit

(2) Other several (learn)

Create directory: MD

Delete directory: Rd

To create a file:

Edit Win7 may not be able to find the command.
There is another way to do this: Notepad
Fallback directory:
Single-level fallback CD:
Multi-level fallback cd\

To delete a file:

Delete a single file del a.txt
Delete multiple Files del *.txt

Show contents in directory: Dir

To delete a directory with content:

RD +/S folder name (asking whether to delete)
RD +/q +/S folder name (delete directly)

4:java Language Overview (Learn)

(1) The history of the Java language

Java's father J

DK1.4.2 JDK5 JDK7

(2) The Java language features a number of small features, with a focus on two open source, cross-platform

(3) The Java language is cross-platform, how can I guarantee it? (understanding) We are explaining through the case of translation.

For different operating systems, improve the different JVM to achieve.

(4) Java language platform Javase javame--android java EE

The role and relationship of 5:JDK,JRE,JVM (mastery)

(1) function

JVM: Securing the Java language across platforms

Jre:java the operating environment of the program

Development environment of Jdk:java program

(2) Relationship

Jdk:jre+ Tools jre:jvm+ Class Library

6:JDK download, install, uninstall (master)

(1) Download to official website.   A: Can also go to Baidu search can. B: I'll give it to you.

(2) Installation

A: The green version of the decompression can be used

B: The installation version must be installed step-by-step, generally as long as you click on the next step

Note: It is recommended that all development-related software should not be installed in a directory with Chinese or white space.

(3) Uninstall

A: Green version Delete folder directly

B: Install version A: Control Panel--Add remove program B: Through the Professional software Uninstall tool. (e.g. 360 software Manager uninstall)

7: First Program: HelloWorld case (Master)

1 class HelloWorld {  2public  staticvoid  main (string[] args) {    3      System.out.println ("HelloWorld");    4

(1) Procedure explanation:

The most basic unit of a A:java program is a class, so we're going to define a class. Format: Class name example: Class HelloWorld

B: When writing content in a class, enclose it in curly braces.

To execute a c:java program, you must have the main method. Format: public static void Main (string[] args)

D: To point to those things and enclose them in curly braces.

E: What are you going to do? Today we just made a simple output format: System.out.println ("HelloWorld"); Note: The contents of "" can be changed.

(2) Java program development and execution process:

A: Writing Java source program (. java)

B: Build the. class file by compiling the Javac command

C: Run the. class file with the Java command

8: Common problems (Master)

(1) extension is hidden how to find: Tools--Folder Options--View--Remove the check mark of hidden extensions

(2) We require that the file name and class name be the same. In fact, it is possible not to do so.

However, note: Javac followed by the filename + extension Java followed by the class name without the extension

(3)    Please note that the Java language is strictly case-sensitive. There is also the word don't write wrong.

(4) See illegal characters: \65307 is definitely a Chinese problem. We write procedures that require punctuation marks to be all in English state.

(5) The pairing problem of brackets. In general, the parentheses are paired up.

(6) When the main method is not found in the class HelloWorld, define the main method as a certain format problem for the main method.

9:path environment Variables (master)

(1) The role of the PATH environment variable guarantees that the Javac command can be run in any directory. Similarly, you can configure QQ, etc.

(2) path configuration of two scenarios:

A: Scenario 1 (understanding)

B: Scenario 2 Find the location of the environment variable, new in the system variable: variable name: Java_home Variable Value: D:\develop\Java\jdk1.7.0_60 Modify: Variable name: Path variable Value:%java_ Home%\bin; previous content

10:classpath Environment Variables (understanding)

(1) The function of the CLASSPATH environment variable guarantees that the class file can be run in any directory

(2) CLASSPATH environment variable configuration find the location of the environment variable, new in the system variable: variable name: Classpath Variable Value: E:\JavaSE\day01\code\HelloWorld case

01 Computer and Java Fundamentals (entry level)