Install the Java Runtime Environment in Linux (CentOS) and output Hello World

Install the Java Runtime Environment in Linux (CentOS) and output Hello World

Recently I plan to learn about Hadoop and spark. I need to install the Java Runtime Environment. My system is CentOS.

1. Install jdk
1. Enter the usr directory

Cd/usr

2. Create a java installation directory under the usr directory

Mkdir java

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

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

4. Install jdk

Cd/usr/java

Rpm-ivh jdk-8u45-linux-x64.rpm

5. After the installation is complete, create a link for him 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/jdk
CLASSPATH =.: $ JAVA_HOME/lib/
PATH = $ PATH: $ JAVA_HOME/bin
Export PATH JAVA_HOME CLASSPATH1
8. Restart the machine or source/etc/profile

Sudo shutdown-r now

9. view the 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)

Ii. Output Hello world
1. Create javac helloworld. java

Class Test {
Public static void main (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!
Output result:
-Bash-4.1 # java Test hello world
Test input main arguments
Hello world
End of main