Practical Android skills: Switch JDK under Ubuntu

Practical Android skills: Switch JDK under Ubuntu

After Android L, we recommend that you use JDK 7 to compile the program. This is a natural development rule, just like compiling Android 1.6 4 years ago and using JDK 5.

Multi-version JDK can coexist. You only need to use the update-alternatives tool to switch between them at any time. The following describes how to install openjdk and oracle jdk (cannot cope with sun) and switch the version.

1. Install openjdk7

$ sudo apt-get update$ sudo apt-get install openjdk-7-jdk

Find the installation path after installation:

$ 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

Ii. Switch java version

$ sudo update-alternatives --config javaThere 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 modePress enter to keep the current choice[*], or type selection number: 2update-alternatives: using /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java to provide /usr/bin/java (java) in manual mode.$ java -versionjava version "1.7.0_65"OpenJDK Runtime Environment (IcedTea 2.5.3) (7u71-2.5.3-0ubuntu0.12.04.1)

3. Install the Oracle jdk and use Android Studio for development. When you start the IDE, the following message is displayed:
OpenJDK shows intermittent performance and UI issues. We recommend using the Oracle JRE/JDK.
It seems that the JDK of Oracle is still to be installed, because the JDK is not available in the ubuntu software source, so you cannot use the apt-get tool like installing openjdk.
We still need to download JDK 7 from the official website.

In the past, I put these software under the/opt directory. Decompress JDK to the new directory jdk.
Use the update-alternatives tool to add java optional configuration items (this is a dpkg utility ).

$ 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 is the priority value. I use a random number here.
Check our config:

$ sudo update-alternatives --config javaThere 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 modePress enter to keep the current choice[*], or type selection number: 1update-alternatives: using /opt/jdk/jdk1.7.0_71/bin/java to provide /usr/bin/java (java) in manual mode

Verify whether the switchover is successful:

$ java -versionjava 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)

Similarly, when we need to switch to a lower version, select 2 or install oracle JDK 6 and manage it. In this way, you do not need to manually modify the environment to flexibly switch the JDK version.