Dark Horse programmer ____ First stage Java Development Prelude (1)

　　

Dark Horse programmer ____ First stage Java Development Prelude (1)

⒈ Software Development:

Software is a set of computer data and instructions organized in a specific order, software development is the production of software. The advent of software enables the interaction between people and computers.

⒉ interactive mode:

Graphical interface and command line, graphical interface is simple and intuitive, users are easy to accept, easy to operate. command-line mode needs to have a console, enter specific instructions, let the computer do some operations, more cumbersome, need to remember some commands.

3. Common DOS commands:

dir: Lists the files and folders in the current directory

MD: Create directory (folder)

RD: Deleting a directory

CD: Enter the specified directory

Cd.. : Exits the current directory and returns to the top level directory

Cd\: Go back to the root directory

Del: Delete Files

del*: Delete all Files

del*. file extension: Delete files of the same type

Exit: Exit DOS command line

Echo: Create a file. such as: Echo I can (here is file content) > I can. txt

CLS: Clear Screen

Help: Show all commands and descriptions

Exit: Off

4. What is a computer language:

Language is the way of communication between people, and computer language is the way of communication between man and computer.

5.Java Births:

is a generic term for the Java programming language and Java platform (ie, Java ee, javame, javase) introduced by Sun Microsystems Company in May 1995

6.Java Introduction:

Java is an object-oriented programming language that can compose cross-platform application software, has become the preferred development language for Web applications, is simple and easy to learn, fully object-oriented, safe and reliable, can run on any operating system, since the advent of the very popular.

7.Java Type:

ee (Java 2 Platform Enterprise Edition) is a suite of solutions for developing applications in enterprise environments. The technology system includes the following technologies, such as Servlet JSPs, which are mainly for Web application development.

J2SE (Java 2 Platform standard Edition) is a solution for developing common desktop and business applications. The technology system is the basis of the other two, you can complete the development of some desktop applications, such as the Java version of Minesweeper, QQ and so on.

J2ME (Java 2 Platform Micro Edition) Small edition: A solution for the development of electronic consumer products and embedded devices. The technology system is mainly used in small electronic consumer products, such as mobile phone applications.

The cross-platform of 8.Java language

Since the code compiled by the Java program is not code that can be run directly by the hardware system, it is an "intermediate code"-bytecode. A different Java Virtual machine (JVM) is then installed on different hardware platforms, which are then "translated" by the JVM into code that the corresponding hardware platform can execute. So for Java programmers, there is no need to consider what the hardware platform is. So Java can be cross-platform.

Setting up a 9.Java language environment

What is JRE,JDK:

Jre:java Runtime Environment Java Runtime Environment, including the Java Virtual machine JVM and Java programs required by the core class library, such as the need to run a development of a good Java process Installation of the JRE in the computer.

Jdk:java Development Kit Java SDK, the JDK is provided to Java developers, including Java development tools, also includes the JRE. So with the JDK installed, there is no need to install the JRE separately. The development tools include: Compilation tools (Javac.exe) and packaging Tools (Jar.exe).

Download JDK:

Enter the official website www.oracle.com, click Downloads java for Developer, go to the download page, select Java SE 7u67 JDK Download, go to the download page,

Tick agree, select the appropriate computer operating system version, click on the hit!

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To install the JDK:

Install the directory well, always next

To configure environment variables:

Click-Computer-right-properties-Advanced system settings-environment variables-System variables-New variable name: java_home-new Variable Value: Enter the installation directory you remember before

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Then-find the PATH variable name in the system variable-enter at the top of the variable value:%java_home%\bin;

Then, the environment variable is set to complete!

Verify success:

Click-Start-run-cmd-javac or-java-version      

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10. Keywords, identifiers, notes

Java 's keywords have special meanings for Java Compilers, they are used to represent a data type, or to represent the structure of a program , and the keyword cannot be used as a variable name, method name, class name, package name.

In the Java language, for variables, constants, functions, statement blocks also have names, which we all call Java identifiers, which are used to give classes, objects, methods, variables, interface and a custom data type named.

The identifier is written in 26 English letters, numbers: 0-9 symbols: _$, the rules are: numbers can not start, you can not use keywords!

In the Java writing process we need to comment on some programs, in addition to their own convenience to read, more people understand their own programs, so we need to make some comments, can be a programming idea or the role of the program, in a word is to facilitate their own others better Read.

1,//Comment line

2,/* ... * * Note several lines 3,/**......*/document comments

11.Java Program development Experience-hello World

Write the comment before writing the code

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Dark Horse programmer ____ First stage Java Development Prelude (1)