Java

Last updated: 2019-08-09 14:28:03

PDF

JDK is the SDK for Java. This document takes JDK 1.7 and 1.8 as examples to describe how to install and configure JDK under Windows and Linux systems.

Windows

1. Download JDK

Go to the Oracle official website to download an appropriate JDK version for installation.

2. Install

Install JDK as instructed in the default directory (C drive) or a custom installation directory. In this example, we use the following directories:
D:\Program Files\Java\jdk1.8.0_31
D:\Program Files\Java\jre1.8.0_31

3. Configure

After the installation is completed, right click Computer, and then click Properties -> Advanced system settings -> Environment Variables -> System variables -> New to configure the software.
Variable name (N): JAVA_HOME
Variable value (V): D:\Program Files\Java\jdk1.8.0_31 (Configure according to your actual installation path).
Variable name (N): CLASSPATH
Variable value (V): .;%JAVA_HOME%\lib\dt.jar;%JAVA_HOME%\lib\tools.jar; (Note that the variable value begins with ..).
Variable name (N): Path
Variable value (V): %JAVA_HOME%\bin;%JAVA_HOME%\jre\bin;

4. Test

Test whether the configuration is successful: Click Start (or shortcut: Win+R) -> Run (enter cmd) -> OK (or press Enter), then enter the command javac and press Enter.

Linux

If openjdk is installed by using yum or apt-get command, the class library may be incomplete, thus leading to errors when you run relevant tools after the installation. Therefore, we recommend that you manually decompress and install JDK. Specific steps are as follows:

1. Download JDK

Go to the Oracle official website to download an appropriate JDK version for installation.

You need to download a version for Linux. Take jdk-8u151-linux-x64.tar.gz as an example. The file you downloaded may be another version, but the suffix of your file must be .tar.gz.

2. Create a directory

Create a java directory in the /usr/ directory.
shell mkdir /usr/java cd /usr/java ​
Copy the downloaded file jdk-8u151-linux-x64.tar.gz to the /usr/java/ directory.

3. Decompress JDK

shell tar -zxvf jdk-8u151-linux-x64.tar.gz ​

4. Set environment variables

Edit the /etc/profile file. Add the following content to the profile file and save it:
shell set java environment JAVA_HOME=/usr/java/jdk1.8.0_151 JRE_HOME=/usr/java/jdk1.8.0_151/jre CLASS_PATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:$JRE_HOME/lib PATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/bin export JAVA_HOME JRE_HOME CLASS_PATH PATH ​

JAVA_HOME and JRE_HOME should be configured according to your actual installation path and JDK version.

Implement the change:
shell source /etc/profile ​

5. Test

sh java -version ​
If the java version information appears, it indicates that JDK is installed successfully.
shell java version "1.8.0_151" Java(TM) SE Runtime Environment (build 1.8.0_151-b12) Java HotSpot(TM) 64-Bit Server VM (build 25.151-b12, mixed mode) ​xxxxxxxxxx java version "1.7.0_79" Java(TM) SE Runtime Environment (build 1.7.0_79-b15) Java HotSpot(TM) 64-Bit Server VM (build 24.79-b02, mixed mode)