JDK 7とJDK 8を切り替える

JDK 7とJDK 8を切り替えてる方法

JDKを探す

コマンドでパッケージを検索してみましょう。

$ yum search openjdk

Loaded plugins: priorities, update-motd, upgrade-helper
12 packages excluded due to repository priority protections
======================= N/S matched: openjdk =============
java-1.6.0-openjdk.x86_64 : OpenJDK Runtime Environment
java-1.6.0-openjdk-demo.x86_64 : OpenJDK Demos
java-1.6.0-openjdk-devel.x86_64 : OpenJDK Development Environment
java-1.6.0-openjdk-javadoc.x86_64 : OpenJDK API Documentation
java-1.6.0-openjdk-src.x86_64 : OpenJDK Source Bundle
java-1.7.0-openjdk.x86_64 : OpenJDK Runtime Environment
java-1.7.0-openjdk-demo.x86_64 : OpenJDK Demos
java-1.7.0-openjdk-devel.x86_64 : OpenJDK Development Environment
java-1.7.0-openjdk-javadoc.noarch : OpenJDK API Documentation
java-1.7.0-openjdk-src.x86_64 : OpenJDK Source Bundle
java-1.8.0-openjdk.x86_64 : OpenJDK Runtime Environment
java-1.8.0-openjdk-demo.x86_64 : OpenJDK Demos
java-1.8.0-openjdk-devel.x86_64 : OpenJDK Development Environment
java-1.8.0-openjdk-headless.x86_64 : OpenJDK Runtime Environment
java-1.8.0-openjdk-javadoc.noarch : OpenJDK API Documentation
java-1.8.0-openjdk-javadoc-zip.noarch : OpenJDK API Documentation compressed in single archive
java-1.8.0-openjdk-src.x86_64 : OpenJDK Source Bundle

JDK1.8をインストール

$ yum install java-1.8.0-openjdk
#
# インストールした Java のバージョンが表示されれば確認終了です。
#
$ java --version

java version "1.8.0_141"

JDK 7→JDK 8の場合に

$ java -version
#
# output
# java version "1.7.0_151"
# ....
#
$ alternatives --config java
#
# output
#
# There are 3 programs which provide 'java'.
# 
#   Selection    Command
# -----------------------------------------------
# *+ 1           /usr/lib/jvm/jre-1.7.0-openjdk.x86_64/bin/java
#    2           /usr/lib/jvm/jre-1.8.0-openjdk.x86_64/bin/java
#    3           /usr/lib/jvm/jre-1.6.0-openjdk.x86_64/bin/java
#
# Enter to keep the current selection[+], or type selection number:
#
# input 2
$ java -version
#
# output
# openjdk version "1.8.0_141"
# ......

JDK 8 → JDK 7の場合に

$ java -version
#
# output
# java version "1.8.0_141"
# ....

$ alternatives --config java
#
# output
#
# There are 3 programs which provide 'java'.
# 
#   Selection    Command
# -----------------------------------------------
# *  1           /usr/lib/jvm/jre-1.7.0-openjdk.x86_64/bin/java
#  + 2           /usr/lib/jvm/jre-1.8.0-openjdk.x86_64/bin/java
#    3           /usr/lib/jvm/jre-1.6.0-openjdk.x86_64/bin/java
#
# Enter to keep the current selection[+], or type selection number:
#
# input 1
$ java -version
# output
# openjdk version "1.7.0_151"
# ......

end

皆様のお仕事の役に立てれば幸いです。