Using color in Android, by XML

In Android, colors can be defined directly, such as "#ff0000" for red. You can also create a resource file under /res/values folder (with any file name), with your own color id defined inside. Such that you can access them in Java code using id. Android also defined a base set in android.R.color.

example:



/res/values/mycolor.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
<color name="red">#ff0000</color>
<color name="green">#00ff00</color>
<color name="blue">#0000ff</color>
</resources>

/res/layout/main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:id="@+id/background"
    >

<TextView  
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="@string/hello"
    />
    
<!-- "white" defined in Android base set of colors -->
<Button
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content"  
    android:text="WHITE"
    android:textColor="@android:color/white"
    android:id="@+id/whitebutton"
 />
    
<!-- direct define textColor -->
<Button
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content"  
    android:text="RED"
    android:textColor="#ff0000"
    android:id="@+id/redbutton"
 />
 
<!-- "green" defined in mycolor.xml -->
<Button
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content"  
    android:text="GREEN"
    android:textColor="@color/green"
    android:id="@+id/greenbutton"
 />
 
<!-- "blue" defined in mycolor.xml -->
<Button
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content"  
    android:text="BLUE"
    android:textColor="@color/blue"
    android:id="@+id/bluebutton"
 />
</LinearLayout>