Open jdk && oracle jdk 共存切换

sudo update-alternatives --config java然后提示

There are 2 choices for the alternative java (providing /usr/bin/java).
  Selection    Path                                            Priority   Status
------------------------------------------------------------
  0            /usr/lib/jvm/java-8-oracle/jre/bin/java          1081      auto mode
* 1            /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java   1071      manual mode
  2            /usr/lib/jvm/java-8-oracle/jre/bin/java          1081      manual mode

选一个即可.因为最近编译系统源码不能安装open jdk,而且还不能是1.8的 所以就装了许多版本的java.所以就导致很多问题的发生,此切换支持apt-get安装