Android L之后推薦使用JDK7編譯程序，這是自然發展規律，就像是4年前編譯Android 1.6需要使用JDK5一樣。 多版本JDK是可以共存的，只需要使用update-alternatives工具就可以隨時將它們切換。下面描述安裝openjdk和oracle jdk（對不住了sun）以及切換版本的過程。 #### 一、安裝openjdk7 ~~~ $?sudo?apt-get?update?? $?sudo?apt-get?install?openjdk-7-jdk?? ~~~ 安裝完成后找到其安裝路徑： ~~~ $?dpkg?-L?openjdk-7-jdk?? /.?? /usr?? /usr/lib?? /usr/lib/jvm?? /usr/lib/jvm/java-7-openjdk-amd64?? ?? $?ls?/usr/lib/jvm/java-7-openjdk-amd64/?? ASSEMBLY_EXCEPTION??bin??docs??include??jre??lib??man??src.zip??THIRD_PARTY_README?? ~~~ #### 二、切換java版本 ~~~ $?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-6-openjdk-amd64/jre/bin/java???1061??????auto?mode?? ??1????????????/usr/lib/jvm/java-6-openjdk-amd64/jre/bin/java???1061??????manual?mode?? ??2????????????/usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java???1051??????manual?mode?? ?? Press?enter?to?keep?the?current?choice[*],?or?type?selection?number:?2?? update-alternatives:?using?/usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java?to?provide?/usr/bin/java?(java)?in?manual?mode.?? ?? $?java?-version?? java?version?"1.7.0_65"?? OpenJDK?Runtime?Environment?(IcedTea?2.5.3)?(7u71-2.5.3-0ubuntu0.12.04.1)?? ~~~ #### 三、安裝Oracle jdk 使用Android Studio做開發，啟動IDE就提示： OpenJDK shows intermittent performance and UI issues. We recommend using the Oracle JRE/JDK. 看來還是要安裝Oracle的JDK了，因為ubuntu軟件源中沒有此JDK，所以不能像安裝openjdk一樣使用apt-get工具。 那么我們還是要去[官網下載jdk7](http://www.oracle.com/technetwork/java/javase/downloads/jdk7-downloads-1880260.html)。 按照以往的慣例，我將這些軟件放在/opt目錄下。將JDK解壓到新建目錄jdk下。 用update-alternatives工具來添加java可選配置項（這是一個dpkg的一個實用工具）。 ~~~ $?sudo?update-alternatives?--install?/usr/bin/java?java?/opt/jdk/jdk1.7.0_71/bin/java?700?? $?sudo?update-alternatives?--install?/usr/bin/javac?javac?/opt/jdk/jdk1.7.0_71/bin/javac?700?? $?sudo?update-alternatives?--install?/usr/bin/jar?jar?/opt/jdk/jdk1.7.0_71/bin/jar?700?? ~~~ 700是優先級數值，我這里隨便使用了一個數。 查看一下我們的config： ~~~ $?sudo?update-alternatives?--config?java?? There?are?3?choices?for?the?alternative?java?(providing?/usr/bin/java).?? ?? ??Selection????Path????????????????????????????????????????????Priority???Status?? ------------------------------------------------------------?? ??0????????????/usr/lib/jvm/java-6-openjdk-amd64/jre/bin/java???1061??????auto?mode?? ??1????????????/opt/jdk/jdk1.7.0_71/bin/java????????????????????700???????manual?mode?? ??2????????????/usr/lib/jvm/java-6-openjdk-amd64/jre/bin/java???1061??????manual?mode?? *?3????????????/usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java???1051??????manual?mode?? ?? Press?enter?to?keep?the?current?choice[*],?or?type?selection?number:?1?? update-alternatives:?using?/opt/jdk/jdk1.7.0_71/bin/java?to?provide?/usr/bin/java?(java)?in?manual?mode?? ~~~ 驗證是否切換成功： ~~~ $?java?-version?? java?version?"1.7.0_71"?? Java(TM)?SE?Runtime?Environment?(build?1.7.0_71-b14)?? Java?HotSpot(TM)?64-Bit?Server?VM?(build?24.71-b01,?mixed?mode)?? ~~~ 同樣的，當我們需要切換到低版本時選擇2或者安裝oracle jdk6并將其納入管理。這樣就可以不用通過手動修改環境的方式來靈活切換JDK的版本了。