Default how to compile java to class

am trying to compile java to class

Code:
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javac dumy_class.java
give me error
Code:
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 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