title: why can't I run java in ubuntu even with these commands?
body: <p>I just entered command like this.</p>
  
  <pre><code>stillily@ubuntu:~$ cd Desktop/
  stillily@ubuntu:~/Desktop$ cd jdk1.8.0_51/
  stillily@ubuntu:~/Desktop/jdk1.8.0_51$ cd bin/
  stillily@ubuntu:~/Desktop/jdk1.8.0_51/bin$ ls
  appletviewer  jar        javadoc         javapackager  jconsole  jhat  jmc         jsadebugd  jvisualvm     pack200     rmiregistry  tnameserv  xjc
  ControlPanel  jarsigner  javafxpackager  java-rmi.cgi  jcontrol  jinfo  jmc.ini     jstack     keytool       policytool  schemagen    unpack200
  extcheck      java       javah           javaws        jdb       jjs    jps         jstat      native2ascii  rmic        serialver    wsgen
  idlj          javac      javap           jcmd          jdeps     jmap   jrunscript  jstatd     orbd          rmid        servertool   wsimport
  stillily@ubuntu:~/Desktop/jdk1.8.0_51/bin$ java
  The program 'java' can be found in the following packages:
  </code></pre>
  
  <p>And it confused me a lot that just this morning I can run java correctly.</p>