activity_main.xml

<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
            xmlns:app="http://schemas.android.com/apk/res-auto"
            xmlns:tools="http://schemas.android.com/tools"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            tools:context=".MainActivity">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical">

        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Date"/>

        <net.imknown.bettertextclockbackportlibrary.TextClock
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:format12Hour="yyyy/MM/dd EEEE"
            app:format24Hour="yyyy/MM/dd EEEE"/>

        <net.imknown.bettertextclockbackportlibrary.TextClock
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:format12Hour="y/M/d E"
            app:format24Hour="y/M/d E"/>

        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="\nNormal"/>

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content">

            <Button
                android:id="@+id/focus_use_12"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="focus 12"/>

            <Button
                android:id="@+id/focus_use_24"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="focus 24"/>

            <Button
                android:id="@+id/use_system"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="system"/>

        </LinearLayout>

        <net.imknown.bettertextclockbackportlibrary.TextClock
            android:id="@+id/normal"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>

        <!-- ===================================================== -->

        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="\nForce use 12 format"/>

        <net.imknown.bettertextclockbackportlibrary.TextClock
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:forceUse="format12"
            app:format12Hour="a h:m:s"/>

        <net.imknown.bettertextclockbackportlibrary.TextClock
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:forceUse="format12"
            app:format12Hour="a hh:mm:ss"/>

        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="\nForce use 24 format"/>

        <net.imknown.bettertextclockbackportlibrary.TextClock
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:forceUse="format24"
            app:format24Hour="k:m:s"/>

        <net.imknown.bettertextclockbackportlibrary.TextClock
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:forceUse="format24"
            app:format24Hour="kk:mm:ss"/>

        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="\nUse system format"/>

        <net.imknown.bettertextclockbackportlibrary.TextClock
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:forceUse="formatAuto"
            app:format12Hour="a h:m:s"
            app:format24Hour="k:m:s"/>

        <net.imknown.bettertextclockbackportlibrary.TextClock
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:forceUse="formatAuto"
            app:format12Hour="a hh:mm:ss"
            app:format24Hour="kk:mm:ss"/>

        <!-- ===================================================== -->

        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="\nH and HH for 24 can be used above API 17 only"/>

        <net.imknown.bettertextclockbackportlibrary.TextClock
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:forceUse="format24"
            app:format24Hour="H:m:s"/>

        <net.imknown.bettertextclockbackportlibrary.TextClock
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:forceUse="format24"
            app:format24Hour="HH:mm:ss"/>

        <!-- ===================================================== -->

        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="\nGMT, Washington D.C. and Tokyo"/>

        <net.imknown.bettertextclockbackportlibrary.TextClock
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:forceUse="format12"
            app:format12Hour="y/M/d E a h:m:s"
            app:timeZone="GMT-6"/>

        <net.imknown.bettertextclockbackportlibrary.TextClock
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:forceUse="format12"
            app:format12Hour="y/M/d E a h:m:s"
            app:timeZone="GMT+9"/>
    </LinearLayout>

</ScrollView>