Jtdcftul

I'm not facing an actual issue yet, rather trying to avoid any...

Currently, these packages are installed on my PC (automatically installed during a fresh install of Kubuntu 14.04):

$ apt list openjdk* --installed

Listing... Done

**openjdk-6-jdk**/trusty-updates,trusty-security,now 6b36-1.13.8-0ubuntu1~14.04 amd64 [installed,automatic]

**openjdk-6-jre**/trusty-updates,trusty-security,now 6b36-1.13.8-0ubuntu1~14.04 amd64 [installed,automatic]

**openjdk-6-jre-headless**/trusty-updates,trusty-security,now 6b36-1.13.8-0ubuntu1~14.04 amd64 [installed,automatic]

**openjdk-6-jre-lib**/trusty-updates,trusty-security,now 6b36-1.13.8-0ubuntu1~14.04 all [installed,automatic]

**openjdk-7-doc**/trusty-updates,trusty-security,now 7u79-2.5.6-0ubuntu1.14.04.1 all [installed,automatic]

**openjdk-7-jre**/trusty-updates,trusty-security,now 7u79-2.5.6-0ubuntu1.14.04.1 amd64 [installed]

**openjdk-7-jre-headless**/trusty-updates,trusty-security,now 7u79-2.5.6-0ubuntu1.14.04.1 amd64 [installed]

May I safely leave these packages present on my PC and install Oracle JDK 8 from Oracle.com along with these older versions of Java?

And is there any recommendation regarding the installation directory for Oracle JDK 8?

Thank you in advance for your suggestions.

Ok, everything went ok and here is how I did briefly:

• 
  

  I left OpenJDK 6&7 installed on my PC. Apparently no problem installing Oracle JDK8 along with them, in a dedicated directory. I only added these lines to my ~/.profile at the end of the whole installation process to be sure to be using JDK/JRE 8 at all times:

  
  
  

  export JAVA_HOME=/usr/local/bin/jdk1.8.0_51
  
  export PATH=$JAVA_HOME/bin:$PATH
  
  

  
  

Note: JAVA_HOME wasn't set previously.

• followed tutorial http://www.tecmint.com/html5-mobile-web-development-using-netbeans-and-java/ to install JDK and NetBeans (adapted a bit to the most recent JDK/NetBeans releases and to my needs - no intention to develop HTML5 applications, so I downloaded the "Java SE" edition of NetBeans).



• 
  

  Installation directories I chose (I actually conformed to the tutorial):

  
  
  

  /usr/local/bin #for JDK.
  
  /usr/local #for NetBeans.
  
  

  
  

Addition:

Some time later I realized that double-clicking on a .jar file was still launching "OpenJDK Java 6 Runtime" (cautious-launcher %f /usr/bin/java -jar) by default.

So I added a new entry (later set as the preferred one) in KDE's File Association preferences, for known type "application > x-java-archive":

[Name = Oracle JDK 8 Runtime]  

[Command = cautious-launcher %f /usr/local/bin/jdk1.8.0_51/bin/java -jar] 

Note: as for existing entry "OpenJDK Java 6 Runtime", .jar applications will not be allowed to execute except if their Executable bit is set (to be set manually if needed) - refer to "cautious-launcher".