How to change the spinner background in Android?

Even though it is an older post but as I came across it while looking for same problem so I thought I will add my two cents as well. Here is my version of Spinner's background with DropDown arrow. Just the complete background, not only the arrow.

This is how it looks..

Apply on spinner like...

<Spinner
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
     android:background="@drawable/spinner_bg" />

spinner_bg.xml

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <color android:color="@color/InputBg" />
    </item>
    <item android:gravity="center_vertical|right" android:right="8dp">
        <layer-list>
            <item android:width="12dp" android:height="12dp" android:gravity="center" android:bottom="10dp">
                <rotate
                    android:fromDegrees="45"
                    android:toDegrees="45">
                    <shape android:shape="rectangle">
                        <solid android:color="#666666" />
                        <stroke android:color="#aaaaaa" android:width="1dp"/>
                    </shape>
                </rotate>
            </item>
            <item android:width="30dp" android:height="10dp" android:bottom="21dp" android:gravity="center">
                <shape android:shape="rectangle">
                    <solid android:color="@color/InputBg"/>
                </shape>
            </item>
        </layer-list>
    </item>
</layer-list>

@color/InputBg should be replaced by the color you want as your background.

First it fills the background with desired color. Then a child layer-list makes a square and rotates it by 45 degrees and then a second Rectangle with background color covers the top part of rotated square making it look like a down arrow. (There is an extra stroke in rotated rectangle with is not really required)

You can change background color and drop down icon like doing this way

Step1: In drawable folder make background.xml for border of spinner.

<shape xmlns:android="http://schemas.android.com/apk/res/android">
<solid android:color="@android:color/transparent" />
<corners android:radius="5dp" />
<stroke
    android:width="1dp"
    android:color="@color/darkGray" />
</shape>  //edited

Step2: for layout design of spinner use this drop down icon or any image drop.pnj

  <RelativeLayout
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:layout_marginRight="3dp"
                    android:layout_weight=".28"
                    android:background="@drawable/spinner_border"
                    android:orientation="horizontal">

                    <Spinner
                        android:id="@+id/spinner2"
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:layout_centerVertical="true"
                        android:layout_gravity="center"
                        android:background="@android:color/transparent"
                        android:gravity="center"
                        android:layout_marginLeft="5dp"
                        android:spinnerMode="dropdown" />

                    <ImageView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:layout_alignParentRight="true"
                        android:layout_centerVertical="true"
                        android:layout_gravity="center"
                        android:src="@mipmap/drop" />

                </RelativeLayout>

Finally looks like below image and it is every where clickable in round area and no need of to write click Lister for imageView.

For more details , you can see Here

When you set the spinner background color using android:background="@color/your_color" your spinner default arrow will disappear

And also need to add fixed width and height to spinner so you can show the full content of the spinner.

so i found a way to do it , just like the above image.

Write your spinner code inside a frame layout, here you don't need to use a separate image view for showing drop down icon.

  <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Floor"
            android:textColor="@color/white"/>

        <FrameLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="@dimen/margin_short"
            android:background="@drawable/custom_spn_background">

            <Spinner
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:dropDownSelector="@color/colorAccent"
                android:dropDownWidth="@dimen/dp_70"
                android:spinnerMode="dropdown"
                android:tooltipText="Select floor" />
        </FrameLayout>

Create a new xml for Frame layout background or set android:background="@color/your_color"

custom_spn_background.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<corners android:radius="@dimen/dp_5" />
<solid android:color="@color/white" />

You can set the spinners background color in xml like this:

android:background="YOUR_HEX_COLOR_CODE"

and if you use the drop down menu with you spinner you can set its background color like this:

android:popupBackground="YOUR_HEX_COLOR_CODE"