Could someone help me with this flat button design? topic

I found the following link htt/ps://github.co/m/hoang8f/android-flat-button . I copied
everything as he said, and I use it in xml and I can see in the preview that I have a specific design that looks close to his design

<RelativeLayout xmlns:android="htt/p://schemas.android.co/m/apk/res/android"
xmlns:fbutton="ht/tp://schemas.android.co/m/apk/res-auto"
xmlns:tools="ht/tp://schemas.android.c/om/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity"
>
<info.hoang8f.widget.FButton
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="left|top"
android:layout_margin="10dp"
android:minHeight="@dimen/demo_button_min_height"
android:minWidth="@dimen/demo_button_min_width"
android:text="@string/buttonString"
android:textColor="@android:color/white"
fbutton:buttonColor="@color/fbutton_color_emerald"
fbutton:shadowEnabled="true" />
</RelativeLayout>

but I get this error

Error:Execution failed for task ':app:dexDebug'.
> com.android.ide.common.internal.LoggedErrorExcepti on: Failed to run command:
C:\Users\userpc\AppData\Local\Android\sdk\build-tools.1.2\dx.bat --dex --no-optimize --output C:\Users\userpc\AndroidStudioProjects\Project\app\ build\intermediates\dex\debug --input-list=C:\Users\userpc\AndroidStudioProjects\Project \app\build\intermediates\tmp\dex\debug\inputList.t xt
Error Code:
2
Output:
UNEXPECTED TOP-LEVEL EXCEPTION:
com.android.dex.DexException: Multiple dex files define Linfo/hoang8f/widget/FButton;
at com.android.dx.merge.DexMerger.readSortableTypes(D exMerger.java:596)
at com.android.dx.merge.DexMerger.getSortedTypes(DexM erger.java:554)
at com.android.dx.merge.DexMerger.mergeClassDefs(DexM erger.java:535)
at com.android.dx.merge.DexMerger.mergeDexes(DexMerge r.java:171)
at com.android.dx.merge.DexMerger.merge(DexMerger.jav a:189)
at com.android.dx.command.dexer.Main.mergeLibraryDexB uffers(Main.java:454)
at com.android.dx.command.dexer.Main.runMonoDex(Main. java:303)
at com.android.dx.command.dexer.Main.run(Main.java:24 6)
at com.android.dx.command.dexer.Main.main(Main.java:2 15)
at com.android.dx.command.Main.main(Main.java:106)