util java ionic

1.Remove all the Java related packages (Sun, Oracle, OpenJDK, IcedTea plugins, GIJ):

dpkg-query -W -f='${binary:Package}\n' | grep -E -e '^(ia32-)?(sun|oracle)-java' -e '^openjdk-' -e '^icedtea' -e '^(default|gcj)-j(re|dk)' -e '^gcj-(.*)-j(re|dk)' -e '^java-common' | xargs sudo apt-get -y remove
sudo apt-get -y autoremove
2.Purge config files (careful. This command removed libsgutils2-2 and virtualbox config files too):

dpkg -l | grep ^rc | awk '{print($2)}' | xargs sudo apt-get -y purge
3.Remove Java config and cache directory:

sudo bash -c 'ls -d /home/*/.java' | xargs sudo rm -rf
4.Remove manually installed JVMs:

sudo rm -rf /usr/lib/jvm/*
5.Remove Java entries, if there is still any, from the alternatives:

for g in ControlPanel java java_vm javaws jcontrol jexec keytool mozilla-javaplugin.so orbd pack200 policytool rmid rmiregistry servertool tnameserv unpack200 appletviewer apt extcheck HtmlConverter idlj jar jarsigner javac javadoc javah javap jconsole jdb jhat jinfo jmap jps jrunscript jsadebugd jstack jstat jstatd native2ascii rmic schemagen serialver wsgen wsimport xjc xulrunner-1.9-javaplugin.so; do sudo update-alternatives --remove-all $g; done
6.Search for possible remaining Java directories:

sudo updatedb
sudo locate -b '\pack200'
7.Install JAVA-8-SDK

sudo add-apt-repository ppa:webupd8team/java
sudo apt-get install oracle-java8-installer
8.Open sudo gedit ~/.bashrc and add these lines

export ANDROID_SDK_ROOT=/yourAndroidStudioPath/Android
export PATH=${PATH}:$ANDROID_SDK_ROOT/tools:$ANDROID_SDK_ROOT/platform-tools
export JAVA_HOME=/usr/lib/jvm/java-8-oracle
export JRE_HOME=/usr/lib/jvm/java-8-oracle/jre
Try to run your ionic app again :)
Njoy!