how to compile java to class

[darkc99]

am trying to compile java to class

javac dumy_class.java

give me error

 error: package android.util does not exist

i know that package is inside android.jar

path to my android sdk is : C:\Program Files\Android\android-studio\sdk\platforms\android-19\
and my java file path is : C:\dumy_class.java

so please how can i compile so that i get class ...... after that my target is to get dex file

so please help

thanks