Change Spinner dropdown icon

We can manage it by hiding the icon as i did:

<FrameLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
    <Spinner android:id="@+id/fragment_filter_sp_users"
             android:layout_width="match_parent"
             android:background="@color/colorTransparent"
             android:layout_height="wrap_content"/>

    <ImageView
            android:layout_gravity="end|bottom"
            android:contentDescription="@null"
            android:layout_marginBottom="@dimen/_5sdp"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/ic_arrow_bottom"
    />
</FrameLayout>

For this you can use .9 Patch Image and just simply set it in to background.

android:background="@drawable/spin"

Here i'll give you .9patch image. try with this.

Right click on image and click Save Image as

set image name like this : anyname.9.png and hit save.

Enjoy.. Happy Coading. :)

Add theme to spinner

<Spinner style="@style/SpinnerTheme"
      android:layout_width="match_parent"
      android:layout_height="match_parent"/>

Add spinnerTheme to styles.xml

<style name="SpinnerTheme" parent="android:Widget.Spinner">
    <item name="android:background">@drawable/spinner_background</item>
</style>

Add New -> "Vector Asset" to drawable with e.g. "ic_keyboard_arrow_down_24dp"

Add spinner_background.xml to drawable

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <layer-list>
            <item android:drawable="@drawable/ic_keyboard_arrow_down_24dp" android:gravity="center_vertical|right" android:right="5dp"/>
        </layer-list>
    </item>
</selector>

Try applying following style to your spinner using

style="@style/SpinnerTheme"

//Spinner Style:

<style name="SpinnerTheme" parent="android:Widget.Spinner">
    <item name="android:background">@drawable/bg_spinner</item>
</style>

//bg_spinner.xml Replace the arrow_down_gray with your arrow

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">

    <item>

        <layer-list>

            <item>
                <shape>
                    <gradient android:angle="90" android:endColor="#ffffff" android:startColor="#ffffff" android:type="linear" />

                    <stroke android:width="0.33dp" android:color="#0fb1fa" />

                    <corners android:radius="0dp" />

                    <padding android:bottom="3dp" android:left="3dp" android:right="3dp" android:top="3dp" />
                </shape>
            </item>

            <item android:right="5dp">

                <bitmap android:gravity="center_vertical|right" android:src="@drawable/arrow_down_gray" />

            </item>

        </layer-list>

    </item>

</selector>