Colors are usually stored in a resource file named colors.xml in the /res/values/ folder.

They are defined by <color> elements:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <color name="colorPrimary">#3F51B5</color>
    <color name="colorPrimaryDark">#303F9F</color>
    <color name="colorAccent">#FF4081</color>

    <color name="blackOverlay">#66000000</color>
</resources>

Colors are represented by hexadecimal color values for each color channel (0 - FF) in one of the formats:

• #RGB
• #ARGB
• #RRGGBB
• #AARRGGBB

Legend

• A - alpha channel - 0 value is fully transparent, FF value is opaque
• R - red channel
• G - green channel
• B - blue channel

Defined colors can be used in XML with following syntax @color/name_of_the_color

For example:

<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/blackOverlay">

Using colors in code

These examples assume this is an Activity reference. A Context reference can be used in its place as well.

int color = ContextCompat.getColor(this, R.color.black_overlay);
view.setBackgroundColor(color);

int color = this.getResources().getColor(this, R.color.black_overlay);
view.setBackgroundColor(color);