我只是跑了这个：
java -version
但它给出了这个错误：
The program 'java' can be found in the following packages:
* default-jre
* gcj-4.9-jre-headless
* openjdk-7-jre-headless
* gcj-4.8-jre-headless
* openjdk-6-jre-headless
* openjdk-8-jre-headless
Try: apt-get install <selected package>