我一直在安装 jdk
我有多个问题
1.在第一行，当我尝试设置 java 的替代方案时，它说 java 已经被管理，这是什么意思
2.为什么我必须输入 java1、javac1。我不能输入 java2、javac2 吗？
3.当我尝试设置备用 java 时，它说我有 3 种不同的优先级状态，其中前两个是相同的，并且自动模式和手动模式之间存在差异。
4.最后一行我选择java2，会有什么不同吗？我可以自由选择任意数字吗？
neeraj@dodo:/$ sudo update-alternatives --install /usr/bin/java javac /usr/lib/jvm/jdk1.8.0_72/bin/javac 1
[sudo] password for neeraj:
update-alternatives: error: alternative link /usr/bin/java is already managed by java
neeraj@dodo:/$ sudo update-alternatives --install /usr/bin/java java /usr/lib/jvm/jdk1.8.0_72/bin/java 1
neeraj@dodo:/$ sudo update-alternatives --install /usr/bin/javaws javaws /usr/lib/jvm/jdk1.8.0_72/bin/javaws 1
update-alternatives: using /usr/lib/jvm/jdk1.8.0_72/bin/javaws to provide /usr/bin/javaws (javaws) in auto mode
neeraj@dodo:/$ sudo update-alternatives --config javac
update-alternatives: error: no alternatives for javac
neeraj@dodo:/$ 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/jdk1.8.0_72/bin/java 1 manual mode
Press enter to keep the current choice[*], or type selection number: 2
update-alternatives: using /usr/lib/jvm/jdk1.8.0_72/bin/java to provide /usr/bin/java (java) in manual mode
neeraj@dodo:/$ sudo update-alternatives --config javaws
There is only one alternative in link group javaws (providing /usr/bin/javaws): /usr/lib/jvm/jdk1.8.0_72/bin/javaws
Nothing to configure.
neeraj@dodo:/$ java -version
java version "1.8.0_72"
Java(TM) SE Runtime Environment (build 1.8.0_72-b15)
Java HotSpot(TM) 64-Bit Server VM (build 25.72-b15, mixed mode)
neeraj@dodo:/$ sudo update-alternatives --install /usr/bin/java java /usr/lib/jvm/jdk1.8.0_72/bin/java 1
[sudo] password for neeraj:
neeraj@dodo:/$ sudo update-alternatives --install /usr/bin/java java /usr/lib/jvm/jdk1.8.0_72/bin/java 2
答案1
我关注关联用于安装 Oracle/Sun JDK，它对我来说工作正常。
在一个实例中，我需要手动更新 /etc/environment 中的 JAVA_HOME（通过编辑它）
JAVA_HOME=/path-to-java-before bin directory
export $JAVA_HOME
source /etc/environment
希望这能有效。