Java Development first Step--JDK installation

Jdk,java Development Kit. and JRE, Java Runtime environment.

JDK is 64-bit and 32-bit and can be downloaded to Oracle website by itself

Direct Baidu Download Link

Windows version JDK7 64-bit Http://pan.baidu.com/s/1jGHvtyQ password: j6l1

Linux version JDK7 http://pan.baidu.com/s/1jGLze30 password: xa7o

Windows installation process:

can refer to Baidu Library

 Linux installation process:

1, upload the JDK to the Linux user's desktop (other directories, may not have permission), you can use some upload tools, such as:

Current path:/home/hadoop/desktop/

Flashfxp:http://pan.baidu.com/s/172nym Extract Password: bp6p

Winscp:http://pan.baidu.com/s/1mgl3jks Extract Password: whp2

2, on Linux, the JDK compressed package, placed in the directory you want to install, such as:/usr/local/

Use the command to copy the JDK from/home/hadoop/desktop/to/usr/local/

Cp/home/hadoop/desktop/jdkname/usr/local/jdkname

sudo tar-zxvf jdkname

Detailed use of the tar command:

-Z means that this compressed file is compressed in zip form

-X indicates the meaning of decompression

-V represents view, which shows the process of decompressing

-F means the name of the compressed package is used to understand the extracted folder name.

Update the Java directory name to Java, using the command Mv/usr/local/javaname/usr/local/java

3. Configure Environment variables

Environment variables in Linux are available in a number of places, at the system level and at the user level.

System-level, can modify the file/etc/profile; user level, you can modify the file ~/.BASHRC. User level, which is only valid for the current user, the environment variable is not visible to other users. System-level, which is generic, is available to all Linux users.

In Linux you can use the VI tool to modify text files, such as VI or VIM. The system level is generally modified.

Vim/etc/profile

Append the environment variable at the end of the file:

Export Java_home=/usr/local/java

Export path= $JAVA _home/bin: $PATH (the middle is a colon-delimited)

Then vim can be saved.

Finally, you need to let the configuration take effect, very simple, restart the machine (the average person does not do this), or use Source/etc/profile

Like windows, in command-line mode, enter Javac or Java or java-version to see if the error, no error and the content output is normal

What is the difference between the different versions of JDK?

1. Development efficiency

2, the performance of

3. Java syntax and functionality

For 1 and 2, nothing to talk about. There are some interesting places on the 3.

You can see a lot of information by searching the "JDK version differences" online. More

1.5 new features: Added generics Ah, type conversion AH etc, these in. NET support is better than in Java. More

1.6 New Features: http://www.ibm.com/developerworks/cn/java/j-lo-jse6/

New features of JDK7: IBM detailed description More

jdk1.4 and 1.5 are basically not necessary. By the time this article was released, the JDK has been updated to jdk1.8, to see what new updates are available.

New features of JDK8: lambda expression more

Java Development first Step--JDK installation