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Package openjdk-7-jre-headless is a virtual package provided by:
oracle-java9-installer 9b130+9b130arm-1~webupd8~0
oracle-java8-installer 8u101+8u101arm-1~webupd8~2
oracle-java7-installer 7u80+7u60arm-0~webupd8~1
You should explicitly select one to install.
E: Package 'openjdk-7-jre-headless' has no installation candidate
I'm not sure how to "explicitly select one to install". How do I do that?
sudo apt-get install oracle-java7-installer
for Java version 7 orsudo apt-get install oracle-java8-installer
for Java version 8 orsudo apt-get install oracle-java9-installer
for Java version 9.sudo apt-get install oracle-java8-installer
Replace java8 with 7 or 9 as you want.