Install Java Runtime environment and output Hello World under Linux (CentOS)

Recent plans to learn Hadoop and spark require the installation of the Java Runtime Environment, and the system I use is CentOS.
First, install the JDK
1. Enter the USR directory

Cd/usr

2. Create the Java installation directory in the USR directory

mkdir Java

3. Copy the jdk-8u45-linux-x64.rpm to the Java directory

cp/root/hadoop_home/jdk-8u45-linux-x64.rpm/usr/java/

4. Installing the JDK

Cd/usr/java

RPM-IVH jdk-8u45-linux-x64.rpm

5. Installation completed for him to create a link to save the directory length

Ln-s/usr/java/jdk1.8.0_45//USR/JDK

6. Edit the configuration file

Vim/etc/profile

Add the following content:

JAVA_HOME=/usr/jdkCLASSPATH=.:$JAVA_HOME/lib/PATH=$PATH:$JAVA_HOME/binexport PATH JAVA_HOME CLASSPATH

8. Restart the machine or source/etc/profile

sudo shutdown-r now

9. View installation Status

Java-version

Java Version "1.7.0_25"
OpenJDK Runtime Environment (RHEL-2.3.10.4.EL6_4-X86_64)
OpenJDK 64-bit Server VM (build 23.7-b01, Mixed mode)
Second, the output Hello World
1. Create Javac Helloworld.java

class Test{   publicstaticvoidmain(String []args){                 System.out.println("test input main arguments");                 System.out.println(args[0]+"   "+args[1]);                 System.out.println("end of main");   } }

2. Compile and run
1) Javac Helloworld.java
The Test.class file is generated
2) Java Test.class Hello world!
The output is:
-bash-4.1# java Test Hello World
Test input main arguments
Hello World
End of Main

Install Java Runtime environment and output Hello World under Linux (CentOS)