Define color drawable in XML

We can define our custom color in XML under /res/values/ folder.

example: /res/values/myresources.xml

<resources>
 <drawable name="red_color">#ff0000</drawable>
 <drawable name="blue_color">#0000ff</drawable>
 <drawable name="green_color">#00ff00</drawable>
</resources>

After color defined, it can be acccessed as drawable in XML or using Java code.

<?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"
    >
<TextView  
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="@string/hello"
    />
<TextView  
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="RED in XML"
    android:background="@drawable/red_color" />
<TextView  
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="GREEN in XML"
    android:background="@drawable/green_color" />
<TextView  
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="BLUE in XML"
    android:background="@drawable/blue_color" />
<TextView  
    android:id="@+id/javared"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="RED using Java"/>
<TextView  
    android:id="@+id/javagreen"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="GREEN using Java"/>
<TextView  
    android:id="@+id/javablue"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="BLUE using Java"/>
</LinearLayout>

package com.AndroidTestResources;

import android.app.Activity;
import android.graphics.drawable.ColorDrawable;
import android.os.Bundle;
import android.widget.TextView;

public class AndroidTestResourcesActivity extends Activity {
 
 TextView javaRed, javaGreen, javaBlue;
 
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        javaRed = (TextView)findViewById(R.id.javared);
        javaGreen = (TextView)findViewById(R.id.javagreen);
        javaBlue = (TextView)findViewById(R.id.javablue);
        
        ColorDrawable red = (ColorDrawable)getResources().getDrawable(R.drawable.red_color);
        ColorDrawable green = (ColorDrawable)getResources().getDrawable(R.drawable.green_color);
        ColorDrawable blue = (ColorDrawable)getResources().getDrawable(R.drawable.blue_color);
        
        javaRed.setBackgroundDrawable(red);
        javaGreen.setBackgroundDrawable(green);
        javaBlue.setBackgroundDrawable(blue);
    }
}

Related: Using shape to define round drawable