The shortcut keys and function keys, enter the DOS command line, DOS command to explain, java cross-platform principle, the definition of JRE and JDK, writing format

Shortcut keys and function keys
A: keyboard function keys
* A: the Tab
* B: the Shift
* C: the Ctrl
* D: the Alt
* E: Space
* F: the Enter
* G: the Window
* H: arrow keys
* i: PrtSc (PrintScreen )Screenshots

B: Keyboard shortcuts
a: Ctrl + A Select All
b: Ctrl + C copy
c: Ctrl + V to paste
d: Ctrl + X Cut
e: Ctrl + Z Undo
f: Ctrl + S save
DOS command line entry mode
* A: how to open a DOS console under xp?
* A: Start - Programs - Accessories - Command Prompt
* b: Start - Run -cmd- Enter
* c: win + r-cmd- Enter

B: How to open a DOS console under win7?
a: Start - All Programs - Accessories - Command Prompt
b: Start - Search programs and files -cmd- Enter
c: win + r-cmd- Enter
C: DOS console under win8 how to open
a: Left-click to start - the arrow - a command prompt
b: Right-click start - Search -cmd- Enter
c: Right-click start - run -cmd- Enter
d: win + r-cmd- Enter
DOS command to explain
A: d: Enter letter to switch

B: dir (directory): List files as well as files in the current directory folder
C: cd (change directory) to change the specified directory (into the specified directory)
D: cd ...: back to the last directory
E: ** cd ** : return to the root directory
F: cls: (clear screen) clear screen
G: exit: exit the dos command line (dividing line need to know, to understand under)
/ ============== ===========================================
md (the make Directory): Creating Catalog
rd (remove directory): delete the directory
del (delete): delete files, delete a bunch of the same name suffix .txt files *
notepad to create a file
deletion with the contents of the folder
rd + / s folder name (asking whether to delete)
RD + / q + / s folder name (delete)
the Java cross-platform principle
a: What is cross-platform

B: the principle of cross-platform Java language
as long as the operating system needs to run java applications, install a Java Virtual Machine (JVM Java Virtual Machine) can be. By the JVM is responsible for running Java programs in the system.
C: Java language, cross-platform graphical
write once, run anywhere (a compile, run everywhere)!
What is the JRE and the JDK?
A: What is the JRE?
* Includes the Java Virtual Machine (JVM Java Virtual Machine) and Java program needed the core class libraries, if you want to develop a good run Java programs, the computer can only need to install the JRE.
* JRE: JVM + class library.

B: What is the JDK
the JDK is available to Java developers, which contains the java development tools, including the JRE. So install the JDK, you do not have a separate installation of the JRE.
Which development tools: compiler tools (javac.exe) ** Packaging Tool (jar.exe) ** and other
JDK: JRE + JAVA development tools.
C: Why JDK contains a JRE it?
* End of program development, we need to run it and see the effect.
D: JDK, JRE, JVM roles and relationships

Language written in the format:

1, braces to align and write in pairs
2, a space in front of the opening brace
3, encountered the opening brace to indent, the Tab
4, methods and procedures between the block plus blank lines to make clear the program looks
5, side by side spaces between statements, statements for example
6, operators add spaces

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Origin www.cnblogs.com/qingmuchuanqi48/p/11184678.html