工作中要画些简单的思维导图，于是就安装了 FreeMind，不料它竟然给我报错：

$ freemind 
[warning] /usr/bin/freemind: No java runtime was found
[error] /usr/bin/freemind: Unable to find an appropriate java runtime. See java_wrappers(7) for help

去查查报错原因，vim /usr/bin/freemind：

151     if [ -r /usr/lib/java-wrappers/java-wrappers.sh ]
152     then # the Debian method
153         . /usr/lib/java-wrappers/java-wrappers.sh
154         require_java_runtime java6

从 151 ～ 154 行可知 freemind 想要 Java 6 。
记得当时装了 6 7 8 三个版本的 Java，确认一下：

$ 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-8-oracle/jre/bin/java   8         auto mode
  1            /usr/lib/jvm/java-6-oracle/jre/bin/java   1         manual mode
* 2            /usr/lib/jvm/java-7-oracle/jre/bin/java   7         manual mode
  3            /usr/lib/jvm/java-8-oracle/jre/bin/java   8         manual mode

Press enter to keep the current choice[*], or type selection number: 

可知 Java 6 的目录为 /usr/lib/jvm/java-6-oracle 。

接下来改改配置：

$ sudo cp /usr/lib/java-wrappers/java-wrappers.sh /usr/lib/java-wrappers/java-wrappers.sh.freemind
$ sudo chmod 755 /usr/lib/java-wrappers/java-wrappers.sh.freemind

$ sudo vim /usr/lib/java-wrappers/java-wrappers.sh.freemind，把第 99 行 # DIRS="" 修改为 DIRS="/usr/lib/jvm/java-6-oracle"。

$ sudo vim /usr/bin/freemind，把 java-wrappers.sh 替换为 java-wrappers.sh.freemind。替换后显示如下：

151     if [ -r /usr/lib/java-wrappers/java-wrappers.sh.freemind ]
152     then # the Debian method
153         . /usr/lib/java-wrappers/java-wrappers.sh.freemind
154         require_java_runtime java6

修改完毕，再次启动 FreeMind 一切都好了。