My study record-java SE 01

First, the outline

One, it and computer

1, it's past life

Fifth Generation DT Era

2. Correlation of operating system and platform

1) where the OS is located:

2) Unix Family

3) Windows family

3. Windows common shortcut keys/commands

Second, the computer is very two

1. Taiji and eight monsters

1) Taiji

2) Gossip

3) 64 Gua

2. Overview of the System

The binary system, which is a rounding method, is a kind of carry. For any one of the binary---x-binary, it means that the number operation at a certain position is every X-step. Decimal is every ten into a, hexadecimal is every 16 into a, binary is every two into one, and so on, X-System is every x carry.

1) Two or eight, 16 or 16 binary

Binary: Binary number has two features: It consists of two basic digital 0,1, binary number operation law is every binary one, binary number only two characters 0 and 1, indicating that there are two different stable state components.

Octal: Because the binary data of the base r is small, so the writing and reading of binary data is not convenient, for this reason, the introduction of octal in the mini-system. Octal base r=8=2^3, there are digital 0, 1, 2, 3, 4, 5, 6, 7, and each digital exactly corresponds to three-bit binary number, so octet can well reflect the binary.

Hex: Hexadecimal number has two basic characteristics: It consists of 16 characters 0~9 and a,b,c,d,e,f (they represent the decimal number 10~15), the hexadecimal number operation law is every 16 into one, that is, the base r=16=2^4, usually in the expression with the tail mark H or subscript 16 to show the difference.

2) Computer Data Volume Unit introduction

3, conversion between the binary operation

Specific calculation method

Binary, octal, and hexadecimal conversion tables are easy to calculate:

Note: Each bit of the 8 binary is a 3-bit binary.

4. Original code, anti-code and complement operation

Example: The mutual conversion method between them

Note (the original code of the positive number is the same as the back code)

Third, Sun and Java

1. Computer Language and programming

2. Sun Company and Java Platform

Initially, Java was not so popular, it came from a project by Sun. Gosling inadvertently developed Java as a programming language for this project. Because of the thinking and cross-platform of object-oriented programming, Java later became an unknown programming language.
Later, the project was shelved for some reason. However, the advent of the Internet has brought new opportunities to the development of Java. Before the advent of Java, the information content on the Internet was a tedious and inflexible HTML document. This is simply intolerable for people who are obsessed with web browsing.
Sun's use of the Java language has revolutionized the programming of the Web world.
As for oracle,2009 April 20, Oracle (Oracle) announced the acquisition of Sun.
Since then, Java has become a product of Oracle Corporation.

1) Popular languages

2) SUN

Java founder---James Goslin.

3) Java Platform

4) Android

Android is a free and open source Linux-based operating system that is used primarily for mobile devices such as smartphones and tablets, led and developed by Google and the Open Cell Alliance. There is no unified Chinese name, more people in mainland China use "Android" or "Ann". The Android operating system was originally developed by Andy Rubin, which mainly supports mobile phones. August 2005 was funded by Google's takeover. In November 2007, Google developed an open mobile alliance with 84 hardware manufacturers, software developers and telecoms operators to develop an improved Android system. Google then released the Android source code in the form of an Apache open source license.

3. Javase Course system and learning method

4. Cross-platform/portability

5, realize the cross-platform of arcade game

6. The cross-platform principle of Java

7. JDK-JRE-JVM Overview

File analysis under JDK directory:

Iv. Java Development

1. Build Java development and operating environment

Reference Video: http://www.chuanke.com/v1340360-211360-1316834.html

2. The first Java program

1) Use of workspace:

Directory of Code

Use the Reset menu when the Software toolbar is confusing or needs to be restored to its original state

Create a new program

--Right-click

Note: Use the default location option needs to be checked.

Enter a project name-click Finish

The written code is placed in SRC:

Right-click the project name--Select class to create the program name

Enter the program name at name

2) Java program

Console Simulation window

Note the point:

(1) ' {} ': Represents the scope.

(2) System.out.println: Enter text content to the console.

(3)///text: Comment, explain the content and function of this field, easy to follow to see you and memory.

(4) In the program is divided into 2 positive numbers are also integers, divisor and dividend any one with a decimal result is a decimal, the result of dividing 2 numbers will not be rounded.

(5) When naming a project or file, only letters, numbers, and underscores are included in the name. And the first character cannot be a number.

3. Java Variation and operating mechanism

My study record-java SE 01