在unbuntu14.04系统上安装 Open JDK 8 时遇到了如下问题：
$ sudo apt-get install openjdk-8-jdk Reading package lists... Done Building dependency tree Reading state information... Done E: Unable to locate package openjdk-8-jdk
解决方法：
As you can see I only have java 1.7 installed (on a Ubuntu 14.04 machine).
$ update-java-alternatives -l java-1.7.0-openjdk-amd64 1071 /usr/lib/jvm/java-1.7.0-openjdk-amd64
To install Java 8, I did,
$ sudo add-apt-repository ppa:openjdk-r/ppa $ sudo apt-get update $ sudo apt-get install openjdk-8-jdk
Afterwards, now I have java 7 and 8,
$ update-java-alternatives -l java-1.7.0-openjdk-amd64 1071 /usr/lib/jvm/java-1.7.0-openjdk-amd64 java-1.8.0-openjdk-amd64 1069 /usr/lib/jvm/java-1.8.0-openjdk-amd64
How to switch between different versions?
run the follwing command from the terminal:
$ sudo update-alternatives --config java There are 2 choices for the alternative java (providing /usr/bin/java). Selection Path Priority Status ------------------------------------------------------------ 0 /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java 1071 auto mode 1 /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java 1071 manual mode * 2 /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java 1069 manual mode Press enter to keep the current choice[*], or type selection number:
As you can see I'm running open jdk 8. To switch to to jdk 7, press 1 and hit the Enter key. Do the same for javac,javap,javadoc as well with,:
$ sudo update-alternatives --config javac $ sudo update-alternatives --config javap $ sudo update-alternatives --config javadoc