0 Basic Learning Java Introduction Overview Knowledge (System)

have been concerned about my friends should know, very early on I was going to start writing Java related articles, has not thought about what stage to start. Because it's too simple for everyone, it's too hard to be able to learn. Life is always like this, contradictions and entanglements have been entangled in the body. It's no use thinking about tangled up, it's better to start from scratch. Re-walk the road to self-study, to the 0 basis of the small partners a little direction, to the already work of the Daniel Review the Foundation!

Start today's knowledge below!

First, the basic knowledge of the computer (Java daily programming related)

1, keyboard shortcuts Introduction (Universal shortcut keys, in any IDE writing code are common)

• CTRL + A Select all

• CTRL + C copy

• Ctrl + V Paste

• Ctrl+x Cut

• CTRL + Z Undo

• Ctrl+s Save

2. Common DOS commands

Ii. Overview of the Java language

1. History of Java language

2. Java language Platform version

3. Java language Features

• Simplicity of interpretation

• Object-oriented high performance

• Distributed processing multithreading

• Dynamic dynamics of Robustness

• Structural neutrality security

• Cross-platform (important)

• What is cross-platform?

  Applications written in the Java language can be run on different system platforms

• What is the principle?

  Just install a Java Virtual machine (JVM Java VM) on the operating system that needs to run the Java application. The JVM is responsible for the operation of the Java program in the system.

Third, JDK related download, installation

• JRE (Java Runtime Environment Java Run environment)

• including Java virtual machines (JVM Java) and the core class libraries required by Java programs, if you want to run a well-developed Java program, you only need to install the JRE in your computer

• JDK (Java Development Kit Java Development Kit)

• The JDK is available to Java developers, which includes Java development tools and the JRE. So with the JDK installed, you don't have to install the JRE separately. Development tools: Compilation Tools (Javac.exe) packaging Tools (Jar.exe), etc.

• In simple terms: Java programs developed using the JDK are delivered to the JRE to run

• JDK Download (google/Baidu "java jdk download)

• JDK Installation (fool-mounted, next, installation path do not have Chinese or special symbols such as spaces)

IV. Configuration of environment variables

• The role of the PATH environment variable configuration

• The execution of the program requires the use of an external instruction Javac, but the javac instruction can only be written to the bin directory under the JDK installation directory.

• During the program development process, the source code cannot be written to the JDK's installation directory, so the source program needs to be saved to the specified directory in any location (English directory), so the JAVAC directive needs to be run in any directory

• Path environment variable configuration, CLASSPATH environment variable configuration (no need to set classpath after Java 1.5 version)

• Path/classpath environment variable Configuration please google/Baidu "java environment variable Configuration", according to the first result of the search configuration can be

• The difference between path and classpath

• The PATH environment variable is an executable file, such as an. exe file, where the executable file is located in the current path, and if it is not found, go to the path configured in the PATH environment variable to find

• The directory where the Java class's running files are recorded in the CLASSPATH environment variable

Wu, HelloWorld

• Introduction to Development tools

• Eclipse (most people, recommended 0 basic with Eclipse, tutorials mostly use this tool, error is easy to solve)

• MyEclipse

• STS (Spring Tool Suite)

• IntelliJ idea (trend, recommended to have a development based on the direct start of this model)

• HelloWorld

• First define the class class name

• Add a pair of curly braces {} After the class definition

• Add a main (main) method/function in the middle of the brace public static void Main (String [] args) {}

• Add a row of output statements System.out.println ("Hello World") in the middle of the main method's curly braces;

Six, written in the last, the advice of the experienced

1, now too much programming information, just find a reliable learning video is enough, do not collect so much, simply do not look over.

2, just start to configure the Java environment, it is recommended to follow the learning video configuration, reading configuration error-prone.

3, video and book combined with learning, you can follow the video learning, and then go through the book, deepen understanding. You can't just watch video and learn, and you can't read a book.

4, do not be dead, there are many programming problems, you do not understand now, it's okay! Then learn from the back and you'll understand what's not in front of you.

5, must be more knock code, the important thing said three times: more knock, more knock, more knocking.

6, do not learn to program, only do not try their own. I just learned, with the environment of the place card for three days, and finally a successful career change. So do not begin to encounter difficulties when you give up, you have encountered the problems we have encountered, do not feel stupid!

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