Using shape to define round drawable

To define our shape as a drawable, create XML(s) under /res/drawable/ folder.

/res/drawable/redroundrect.xml

<shape xmlns:android="http://schemas.android.com/apk/res/android">
 <solid 
  android:color="#FFFF0000"/>
 <corners 
  android:radius="15dp" />
 <padding 
  android:left="20dp" 
  android:top="20dp" 
  android:right="20dp" 
  android:bottom="2dp" />
</shape>

/res/drawable/greenroundrect.xml

<shape xmlns:android="http://schemas.android.com/apk/res/android">
 <solid 
  android:color="#FF00FF00"/>
 <corners 
  android:radius="15dp" />
 <padding 
  android:left="20dp" 
  android:top="20dp" 
  android:right="20dp" 
  android:bottom="2dp" />
</shape>

/res/drawable/blueroundrect.xml

<shape xmlns:android="http://schemas.android.com/apk/res/android">
 <solid 
  android:color="#FF0000FF"/>
 <corners 
  android:radius="15dp" />
 <padding 
  android:left="20dp" 
  android:top="20dp" 
  android:right="20dp" 
  android:bottom="2dp" />
</shape>

Using it inside 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"
    >
<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/redroundrect" />
<TextView  
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="GREEN in XML"
    android:background="@drawable/greenroundrect" />
<TextView  
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="BLUE in XML"
    android:background="@drawable/blueroundrect" />
<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>

In Java code

package com.AndroidTestResources;

import android.app.Activity;
import android.graphics.drawable.ColorDrawable;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.GradientDrawable;
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);
        
        Drawable redRoundRect 
        = getResources().getDrawable(R.drawable.redroundrect);
        Drawable greenRoundRect 
        = getResources().getDrawable(R.drawable.greenroundrect);
        Drawable blueRoundRect 
        = getResources().getDrawable(R.drawable.blueroundrect);
        
        javaRed.setBackgroundDrawable(redRoundRect);
        javaGreen.setBackgroundDrawable(greenRoundRect);
        javaBlue.setBackgroundDrawable(blueRoundRect);
    }
}

Related: Define color drawable in XML