Define colors

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);

In above declaration colorPrimary, colorPrimaryDark and colorAccent are used to define Material design colors that will be used in defining custom Android theme in styles.xml. They are automatically added when new project is created with Android Studio.