Schlagwort-Archive: java

Eclipse won’t start with: ObjectNotFoundException: Tree element not found

After installing some Mac OS X Yosemite updates today, my smoothly working Eclipse installation on my Mac Book Pro was broken: starting Eclipse failed with „ObjectNotFoundException: Tree element not found“ permanently!

It seems that the only thing that helps is to delete the „.metadata“ directory in the workspace – at least this solved the problem for me. But be aware of the ugly side-effect that a completely new (and clean) workspace will be created …  :-/

Oracle JDK7 on Ubuntu

How to manually install the official Oracle JDK7 including the Mozilla Firefox Java-Plugin on Ubuntu 12.04 LTS (this example is based on JDK7 update 11 with important security fixes – just replace the version to a more recent one):

download most recent JDK version from Oracle website:


extract to /usr/lib/jvm directly:

  • cd /usr/lib/jvm
  • sudo tar xvzf /path/to/download/folder/jdk-7u11-linux-x64.tar.gz

install the new Java installation to the Ubuntu „alternatives“ system:

  • sudo update-alternatives –install „/usr/bin/java“ „java“ „/usr/lib/jvm/jdk1.7.0_11/bin/java“ 1
  • sudo update-alternatives –install „/usr/bin/javac“ „javac“ „/usr/lib/jvm/jdk1.7.0_11/bin/javac“ 1
  • sudo update-alternatives –install „/usr/bin/javaws“ „javaws“ „/usr/lib/jvm/jdk1.7.0_11/bin/javaws“ 1

now configure the alternatives and select the newly available option as default (in the normal case it will be the last option of the list, just check the path to the java installation …)

  • sudo update-alternatives –config java
  • sudo update-alternatives –config javac
  • sudo update-alternatives –config javaws

Install Mozilla Firefox Plugin (for 64bit):

  • mkdir ~/.mozilla/plugins (if not existent yet)
  •  ln -sf /usr/lib/jvm/jdk1.7.0_11/jre/lib/amd64/ ~/.mozilla/plugins/