1. shortcuts and basic

1.CTRL + Shortcuts

A Select
C Copy (note comprising selection) If there is no end of selection and the mouse is a row, copying the contents of the line
V Paste
X cut
Y redo redo revoked step
S save

2.Windows + Shortcuts

D rapid return to the desktop or to quickly switch the current program
L Quick lock screen
E to quickly open My Computer
R fast run

• cmd dos simulation system
• calc calculator
• mspaint drawing board
• notepad Notepad
• services.msc manage all services
• regedit registry (use caution !!!)

Download 3.java development environment

www.Oracle.com

• javase personal free version, small software
• javame mobile version for mobile device development, deprecated
• JAVAEE -> j2ee for enterprise development, and medium-sized software

4.JDK and JRE

The JDK , the Java Development Kits, the Java Development Kit (defines the syntax, IntelliSense, code completion and debugging). Comprising a jre, and no difference separate jre

The JRE , the Java Environment running, the Java runtime environment (runtime environment driven by a number of other languages of the code required)

5. The first Hello world

6.java Development Tools

• notepad start fast, stable, no installation, no code hints
• notepad ++ / editplus start fast, stable, need to have a portion of the code hints
• eclipse start slow, stable, free and open source, you need to install and support the vast majority of code hints, and bug reports served as the ace of java development tools
• idea to start slow, paid version is very stable. supports all code hints. invincible .

7. Identifier

Naming conventions

1. You can use Chinese, but is not recommended
2. Must start with lowercase letters
3. It can contain uppercase and lowercase letters, numbers, underscores and $
4. If you need multiple list, and satisfies starting from the second word capitalized ------- hump nomenclature
5. The identifier must have a particular meaning
6. Define the variable does not allow duplicate names

Eight basic data types

byte short int long double float boolean char

• Type byte bit Range: -128 to 127
• short short integer in the range: -2 ¹⁵ to 2 ¹⁵ -1
• int Integer Range: -2 ^{31 is} ~ 2 ^{31 is} 1 (the default type for all integer type, if located in the range within the specified type, java will be automatically converted to the int type, or an error is thrown)
• long long integer type commonly used by default values and the same range as in the case of type int, need to manually open (add "L" value in the back)
• double Double-precision floating point type. (The default is that all fractional type, if located in the range within the specified type, java directly to the data type is set to double, if the fractional part is exceeded, the excess will be omitted, and finally into a decimal. 1 ) ------- Double integer may be stored, for example: 12 value is 12.0 ( rounded to one decimal )
• float Single-precision floating-point, generally do not. the fractional part of the double half, need to manually turn. (f or added behind the F value) ---- integer float can also be stored, this time without adding F, retention one decimal above.
• boolean boolean values ​​true and false. As a general determination of several conditions, rarely used alone.
• char character types, each character. the need to use ' single quotes modification, allows to set a range of characters Chinese characters / numbers a / a case letters / a special symbol /

Explanation

Description will be abandoned during JDK code compiler is not included in the description .class file

• One-line description
  syntax:
  // Description of
  the range is within one line, do not allow the use of interbank, if interbank, plus a //

• Multi-line description
  syntax:
  / *
  Description of
  * /

• Documentation
  Syntax:
  / **
  content of the document described in
  * /
  generally written prior to the class, is the collective description of the currently visible ape program code can be generated by a document java command.
  Step of generating document descriptions:
  1. Open cmd, switch want to put the location of the document
  2. use javadoc command generates documentation specified code
  3. open the index.html file to view the generated documentation

8.JAVA features

1) Object-oriented
maintenance and development process is relatively stylized, more standardized
2) Distributed
3) robust
program error, or the error is not easily solved readily
4) security
code structure more rigorous / rigid, relatively homogeneous Solution to Problem
5) Portable of
java code to write one, run anywhere principle:. java program running on a jvm (java virtual machine) java virtual machine, jvm can be registered to a variety of platforms (windows / macos / andriod / ios ) by driving, these platforms
can by using jvm java program code or
6) High performance
java program only the first slow compile time, each execution of the subsequent fast
7) multithreading
using cpu polynuclear features that allow a plurality of processors in the program may be work on the core
8) dynamic