1. Install JDK 1.8 64-bit version (especially the latest version is 1.8)
The installation point is closed at the next and last point
64-bit operating system can install 64-bit and 32-bit software
32-bit operating system can only install 32-bit software
2. Configure environment variables
1>
C:\Program Files\Java\jdk1.7.0_80\bin
Copy this path
Computer-> right-click-> properties-> advanced system settings-> environment variables
Click New below
Variable name: JAVA_HOME
Variable value: C: \ Program Files \ Java \ jdk1.7.0_80 \
Find Path
C:\Program Files\Java\jdk1.7.0_80\bin;
Detection:
Press the Windows + R key, enter cmd, and press Enter. A black window appears, and the DOS command window appears.
A bunch of information appears in java carriage return
A bunch of information appears in javac carriage return
Prove that the jdk environment variable is configured correctly.
java-version detects jdk version
Develop java:
1. New text document
2. Write java code
3. Change the file extension to .java
4. Press Windows + R to enter the javac file name.java in the current directory, this is the compilation
5. java file name, this is run
javac is the compile command
java is run command
javac HelloWorld.java will put the file HelloWorld.java
Compile to HelloWorld.class file
HelloWorld.class is a binary file, also known as a bytecode file
Why compile?
Because the .java file cannot be read by the computer, the computer can only read it after compiling it into a binary file
We all know that computers only recognize 0 and 1 computers only recognize binary
Binary octal decimal ...
Life uses decimal 0 to 9 10 numbers
\ t is a space Note: \ t must be inside double quotes
\ n is a newline note: \ n must be inside double quotes
System.out.println (); is the output statement
public static void main(String[]args){}
The entry point of the program is the main method
class
public
static
void no return value
the name of the main method
String
System
out out ..
print printout
Note: How many class files are there after compiling a java file?
Answer: Not fixed, if there are several classes, several will be generated.
A.java is called class A
There can be only one public class in a file, other classes cannot be public
Only one main method can exist in a class.
// The line comment means that a line will be commented
/ * What to comment * / Multi-line comment
Documentation notes
/*
*HelloWorld.java
*2013-4-23
* The first Java program
*/
Note: Code specification
Tools for developing java: text document Disadvantages: no prompt, no line number, no color ...
The three most popular tools for writing java:
Eclipse
Myeclipse, we use Myeclipse
idea
Myeclipse is a plug-in for Eclipse, but later became more and more powerful, put Eclipse
Incorporated into it, more powerful than Eclipse
idea and webstorm are one.
Install Myeclipse and crack and finish watching the video
How to open the package explorer?
Window-Display View-Package Explorer
Change the font:
Window-Preferences-General-Appearance-Color and Font-Basic-Text Font
Save: Ctrl + S
run:
1. Right click-run mode -1 java run program
2. Click the icon in the toolbar
3. Right-click on the file-run mode -1 java run program
hot key:
Alt + / Code hint
Ctrl + D delete a line
How to write the main method quickly
main then Alt + / Enter
Quickly write output statements System.out.println ();
syso then Alt + /
Automatic prompt:
Window-preferences-java-editor-content assist java automatic activation trigger on the right
Quick copy: ctrl + alt + down arrow key (up)
Do not copy: shortcut keys conflict
hot key:
MyEclipse shortcut key 1 (CTRL)
-------------------------------------
Ctrl + 1 quick fix
Ctrl + D: delete the current line
Ctrl + Q to locate the last edited place
Ctrl + L to locate a line
Ctrl + O quickly display OutLine
Ctrl + T quickly display the inheritance structure of the current class
Ctrl + W close the current Editor
Ctrl + K quickly navigate to the next
Ctrl + E quickly displays the current Editor drop-down list
Ctrl + J forward incremental search (after pressing Ctrl + J, each letter editor you enter provides a quick match to locate a certain word, if not, it shows no found in the stutes line,)
Ctrl + Z to return to the state before modification
Ctrl + Y is the opposite of the above operation
Ctrl + / Comment the current line, then press again to cancel the comment
Ctrl + D delete the current line.
Ctrl + Q jump to the last editing place
Ctrl + M to switch the size of the window
Ctrl + I Format Active Elements.
Ctrl + F6 switch to the next Editor
Ctrl + F7 to switch to the next Perspective
Ctrl + F8 to switch to the next View
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MyEclipse shortcut key 2 (CTRL + SHIFT)
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Ctrl + Shift + E displays the manager that manages all currently open Views (you can choose to close, activate, etc.)
Ctrl + Shift + / Auto comment code
Ctrl + Shift + \ Automatically cancel the commented code
Ctrl + Shift + O automatic boot class package
Ctrl + Shift + J reverse incremental search (same as above, but only from back to front)
Ctrl + Shift + F4 close all open Editor
Ctrl + Shift + X all capitalize the currently selected text
Ctrl + Shift + Y to change all currently selected text to lower case
Ctrl + Shift + F format the current code
Ctrl + Shift + M (first put the cursor on the class name of the package to be imported) The role is to add the Import statement
Ctrl + Shift + P to locate the matching character (such as ()) (when positioning the back from the front, the cursor must be inside the matching character, and the back to the front, otherwise
Ctrl + Shift + F Format Document Format Document.
The effect of Ctrl + Shift + O is that the missing Import statement is added, and the redundant Import statement is deleted.
Ctrl + Shift + S save all unsaved files.
Ctrl + Shift + / is this / * ~ * / comment in the code window, and <!-~-> In the JSP file window.
Shift + Ctrl + Enter inserts a blank line in the current line (the principle is the same as the above)
-----------------------------------------
MyEclipse shortcut key 3 (ALT)
-----------------------------------------
Alt + / Code Assistant completes the insertion of some codes and automatically displays prompt information
Alt + ↓ Interactive position of the current line and the following line (especially practical, you can save the first cut and then paste)
Alt + ↑ Interactive position of current line and upper line (same as above)
Alt + ← Previous edit page
Alt + → Next edit page (of course for the above one)
Alt + Enter displays the attributes of the currently selected resource (project, or file or file)
MyEclipse shortcut key 4 (ALT + CTRL)
Alt + CTRL + ↓ Copy the current line to the next line (copy increase)
Alt + CTRL + ↑ Copy the current line to the previous line (duplication added)
-------------------------------------------
MyEclipse shortcut key 5 (ALT + SHIFT)
-------------------------------------------
Alt + Shift + R rename
Alt + Shift + M extraction method
Alt + Shift + C modify the function structure (more practical, N functions call this method, modify it once
Alt + Shift + L extract local variables
Alt + Shift + F changes the local variable in Class to the field variable
Alt + Shift + I merge variables
Alt + Shift + V shift function and variable
Alt + Shift + Z reconstructed regret medicine (Undo) Shift + Enter inserts a blank line in the next line of the current line (the mouse can be anywhere in the current line at this time, not necessarily the last)
Alt + Shift + O (or click the Toggle Mark Occurrences button in the toolbar) When clicking a mark, this mark will be highlighted in yellow elsewhere on this page, and a white square will appear on the right border of the window. Click this square Will jump to this mark.
The following shortcut keys are commonly used in refactoring.I like it and I often sort it out (note: the shortcut keys for general refactoring are all started with Alt + Shift)
--------------------------------------------
MyEclipse shortcut keys (6)
--------------------------------------------
F2 When the tooltip appears when the mouse is over a mark, press F2 to move the mouse away and the tooltip will also show Show Tooltip Description.
F3 jump to the place of declaration or definition.
F5 single-step debugging into the function.
F6 single-step debugging does not enter the inside of the function. If Kingsoft PowerWord 2006 is installed, the shortcut key of "Word Switch" should be changed to something else.
F7 is returned to the calling site from within the function.
F8 is executed until the next breakpoint.