How to Install OpenJDK 8 in Ubuntu 14.04 & 12.04 LTS

FROM:http://blog.csdn.net/x13945/article/details/51800392

How to Install OpenJDK 8 in Ubuntu 14.04 & 12.04 LTS

原文链接:http://ubuntuhandbook.org/index.php/2015/01/install-openjdk-8-ubuntu-14-04-12-04-lts/

OpenJDK Java 8 has been made into official Ubuntu repositories for 14.10 Utopic and higher. For Ubuntu 14.04, Ubuntu 12.04, and Linux Mint 17 users here’s how to install it from PPA.

OpenJDK 8 was released in March 2014. It’s available in Ubuntu Software Center for Ubuntu 14.10 and Ubuntu 15.04. Someone has reported in launchpad asking for packaging openjdk-8 in Ubuntu 14.04, but no luck so far.

As a workaround, you can install OpenJDK 8 from a PPA repository:

First

Open terminal from the Dash or by pressing Ctrl+Alt+T. When it opens, run the command below to add PPA:

sudo add-apt-repository ppa:openjdk-r/ppa

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Type in user password when it asks and hit Enter to continue.

Second

After that, update system package cache and install OpenJDK 8:

sudo apt-get update 

sudo apt-get install openjdk-8-jdk

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遇到的问题解决：

sudo apt -get update后出现如下错误

W: 无法下载 http://ppa.launchpad.net/openjdk-r/ppa/ubuntu/dists/trusty/InRelease  

W: 无法下载 http://ppa.launchpad.net/wine/wine-builds/ubuntu/dists/trusty/InRelease  

W: 无法下载 http://ppa.launchpad.net/openjdk-r/ppa/ubuntu/dists/trusty/Release.gpg  不能连接到 ppa.launchpad.net：http：

W: 无法下载 http://ppa.launchpad.net/wine/wine-builds/ubuntu/dists/trusty/Release.gpg  不能连接到 ppa.launchpad.net：http：

解决方法：移除不再支持的ppa仓库

sudo add-apt-repository --remove ppa:wine/wine-builds

sudo add-apt-repository --remove ppa:openjdk-r/ppa

然后重新操作FIRST和SECOND的内容就可以了（注意电脑要保持联网 ）

Third

If you have more than one Java versions installed on your system. Run below command set the default Java:

sudo update-alternatives --config java

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Type in a number to select a Java version.

set default java version

And set default Java Compiler by running:

sudo update-alternatives --config javac

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Last

Finally check out current Java version by running:

java -version

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It outputs something like this:

openjdk version "1.8.0_01-internal"
OpenJDK Runtime Environment (build 1.8.0_01-internal-b04)
OpenJDK 64-Bit Server VM (build 25.40-b08, mixed mode)