Where is the Java SDK folder in my computer? Ubuntu 12.04

Question

WAY-1 : Updated for the shortest and easy way

Below command will give you the path, But it will only work if java command is working in other words if java path is configured.

readlink -f $(which java) 

Read more at Where can I find the Java SDK in Linux?

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WAY-2 (Better than WAY-1) : Below answer is still working and try it if above command is not working for you.

You need to dig into symbolic links. Below is steps to get Java directory

Step 1:

$ whereis java
java: /usr/bin/java /etc/java /usr/share/java

That tells the command java resides in /usr/bin/java.

Dig again:

Step 2:

$ ls -l /usr/bin/java
lrwxrwxrwx 1 root root 22 2009-01-15 18:34 /usr/bin/java -> /etc/alternatives/java

So, now we know that /usr/bin/java is actually a symbolic link to /etc/alternatives/java.

Dig deeper using the same method above:

Step 3:

$ ls -l /etc/alternatives/java
lrwxrwxrwx 1 root root 31 2009-01-15 18:34 /etc/alternatives/java -> /usr/local/jre1.6.0_07/bin/java

So, thats the actual location of java: /usr/local/jre.....

You could still dig deeper to find other symbolic links.

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Reference : where is java's home dir?

Please use this command:

readlink -f $(which java)

It works for me with Ubuntu gnome.

On my computer the result is:

/usr/lib/jvm/java-7-oracle/jre/bin/java

Regards.

In generally, java gets installed at /usr/lib/jvm . That is where my sun jdk is installed. check if it is same for open jdk also.

$whereis java
java: /usr/bin/java /usr/bin/X11/java /usr/share/java     /usr/share/man/man1/java.1.gz
$cd /usr/bin
$ls -l java
lrwxrwxrwx 1 root root 22 Apr 15  2014 java -> /etc/alternatives/java
$ls -l /etc/alternatives/java
lrwxrwxrwx 1 root root 39 Apr 15  2014 /etc/alternatives/java ->     /usr/lib/jvm/java-7-oracle/jre/bin/java

So,JDK's real location is /usr/lib/jvm/java-7-oracle/

Location of JRE in Ubuntu:

/usr/lib/jvm/java-7-oracle/jre

$ whereis java

java: /usr/bin/java /usr/lib/java /usr/bin/X11/java /usr/share/java /usr/share/man/man1/java.1.gz

On Ubuntu 14.04, it is in /usr/lib/jvm/default-java.