Java Ubuntu：将路径从 OpenJDK 6 更改为 Oracle JDK 7
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Ubuntu: change the path from OpenJDK 6 to Oracle JDK 7
提问by Devendra Singh
After downloading the latest .tar file I ran tar zxvf jdk-7u45-linux-x64.tar.gzto extract java files.
下载最新的 .tar 文件后，我跑去tar zxvf jdk-7u45-linux-x64.tar.gz提取 java 文件。
Set the path in .bashrcfile (vi ~/.bashrc) as below;
如下设置.bashrc文件 ( vi ~/.bashrc) 中的路径；
export JAVA_HOME=/usr/lib/jvm/jdk1.7.0_45/bin/java
export PATH=$PATH:/usr/lib/jvm/jdk1.7.0_45/bin
export JDK_HOME=/usr/lib/jvm/jdk1.7.0_45
export JRE_HOME=/usr/lib/jvm/jre1.7.0_45
Now, running command java -versionor which java, java PATH still pointing to the older java version (java version "1.6.0_27").
现在，运行 commandjava -version或 which java, java PATH 仍然指向旧的 java 版本 ( java version "1.6.0_27")。
I know default ubuntu takes OpenJDK path. I have to change the path as latest version as my system environment variable set in .bashrcfile.
我知道默认的 ubuntu 使用 OpenJDK 路径。我必须将路径更改为最新版本作为我在.bashrc文件中设置的系统环境变量。
Also, sudo update-alternatives --config java
还， sudo update-alternatives --config java
Selection Path Priority Status
------------------------------------------------------------
0 /usr/lib/jvm/java-7-oracle/jre/bin/java 1062 auto mode
1 /usr/lib/jvm/java-6-openjdk/jre/bin/java 1061 manual mode
2 /usr/lib/jvm/java-7-oracle/jre/bin/java 1062 manual mode
* 3 /usr/lib/jvm/jdk1.7.0_45/bin/java 1 manual mode
Press enter to keep the current choice[*], or type selection number: 3
回答by Petter
You probably want to do
你可能想做
export PATH=/usr/lib/jvm/jdk1.7.0_45/bin:$PATH
OpenJDK is probably still in the path, and Linux will use the first javait finds.
OpenJDK 可能仍在路径中，Linux 将使用java它找到的第一个。
If you don't need it, I would recommend uninstalling OpenJDK.
如果您不需要它，我建议您卸载 OpenJDK。
回答by Atropo
Ubuntu (and Debian) have an elegant way to manage libraries like the jdk.
Ubuntu（和 Debian）有一种优雅的方式来管理像jdk.
Using update-alternativesyou can manage multiple jdklibraries on the same system, choosing which one you want to use as the main one.
使用update-alternatives您可以管理jdk同一系统上的多个库，选择您要使用的作为主要库。
First you have to install an alternative for the new installed jdk:
首先，您必须为新安装的 jdk 安装一个替代方案：
sudo update-alternatives --install "/usr/bin/java" "java" "/usr/lib/jvm/jdk1.7.0_45/bin/java" 1
sudo update-alternatives --install "/usr/bin/javac" "javac" "/usr/lib/jvm/jdk1.7.0_45/bin/javac" 1
In this way you install the new jdkas an alternative to the original one.
Then you can choose which one you wan to use:
通过这种方式，您可以安装新的jdk作为原始安装的替代品。然后你可以选择你想使用哪一个：
sudo update-alternatives --config java
sudo update-alternatives --config javac
You will be asked to choose which jdk you want to use, on my system I have:
系统会要求您选择要使用的 jdk，在我的系统上，我有：
There are 2 choices for the alternative java (providing /usr/bin/java).
Selection Path Priority Status
------------------------------------------------------------
0 /usr/lib/jvm/java-6-openjdk-i386/jre/bin/java 1061 auto mode
1 /usr/lib/jvm/java-6-openjdk-i386/jre/bin/java 1061 manual mode
* 2 /usr/lib/jvm/java-7-openjdk-i386/jre/bin/java 1051 manual mode
Press enter to keep the current choice[*], or type selection number:
At any time you can see what alternatives you have for javaor javacusing the --listoption:
您可以随时查看您有哪些替代方案java或javac使用该--list选项：
sudo update-alternatives --list java
sudo update-alternatives --list javac
To see more options check the update-alternativesman page.
要查看更多选项，请查看update-alternatives手册页。
回答by gihandilanka
Try typing the following in your terminal.
尝试在终端中输入以下内容。
sudo update-alternatives --config java
sudo update-alternatives --config java
The output will be some choices and you can select the correct one which installed to your computer.
输出将是一些选择，您可以选择安装到您的计算机的正确选项。
回答by WillC
Run
跑
sudo update-java-alternatives --list
to list off all the Java installations on a machine by name and directory, and then run
按名称和目录列出机器上的所有 Java 安装，然后运行
sudo update-java-alternatives --set [JDK/JRE name e.g. java-8-oracle]
to choose which JRE/JDK to use.
选择要使用的 JRE/JDK。
If you want to use different JDKs/JREs for each Java task, you can run update-alternatives to configure one java executable at a time; you can run
如果您想为每个 Java 任务使用不同的 JDK/JRE，您可以运行 update-alternatives 一次配置一个 Java 可执行文件；你可以跑
sudo update-alternatives --config java[Tab]
to see the Java commands that can be configured (java, javac, javah, javaws, etc). And then
查看可以配置的 Java 命令（java、javac、javah、javaws 等）。进而
sudo update-alternatives --config [javac|java|javadoc|etc.]
will associate that Java task/command to a particular JDK/JRE.
将该 Java 任务/命令关联到特定的 JDK/JRE。
You may also need to set JAVA_HOME for some applications: from this answeryou can use
您可能还需要为某些应用程序设置 JAVA_HOME：从这个答案中，您可以使用
export JAVA_HOME=$(readlink -f /usr/bin/java | sed "s:bin/java::")
for JREs, or
对于 JRE，或
export JAVA_HOME=$(readlink -f /usr/bin/java | sed "s:jre/bin/java::")
for JDKs.
对于 JDK。
回答by Praveen Kumar Verma
Running command in terminal:
在终端运行命令：
sudo update-alternatives --config java
from the command line to set the version of the JRE you want to use as like available version install of java : 1.6 and 1.8
See below :
从命令行设置您要使用的 JRE 版本，就像 java 的可用版本安装：1.6 和 1.8
见下文：
and choose 1 option and set java-6 versionbecause already current choice set in java-8.
并选择 1 个选项并设置 java-6 版本，因为当前选择已在 java-8 中设置。
