Ubuntu未显示Java已安装

Question

I downloaded the .tar.gz of from the offical site and extracted it into /opt/java directory and

$ ls /opt/java

gives

jdk-10.0.1

but when I run

$ java -version

it gives

The program 'java' can be found in the following packages:


* default-jre
* openjdk-8-jre-headless
* gcj-4.8-jre-headless
* gcj-4.9-jre-headless
* gcj-5-jre-headless
* gcj-6-jre-headless
* openjdk-9-jre-headless
Try: sudo apt install <selected package>

Why is not showing the version of java jdk installed?

Answer 1

that means java is intalled but it doesn't know where...

you have to set your JAVA path inside: /etc/profile and must add to that file:

export JAVA_HOME=<your_java_path>
export PATH=$JAVA_HOME/bin:$PATH 

you have to replace

<your_java_path>

for your known current java path