In the below example code I have created Custom Notification in android. Here first I have added ImageView and TextView in activity_main.xml layout. Then I have used NotificationManager class and NotificationService in MainActivity. You can see below example code it clearly describe you How to create Custom Notification in android.

Step(1)activity_main.xml layout-

   <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/layout"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:padding="10dp" >
    <ImageView android:id="@+id/image"
        android:layout_width="wrap_content"
        android:layout_height="fill_parent"
        android:layout_alignParentLeft="true"
        android:layout_marginRight="10dp" />
    <TextView android:id="@+id/title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_toRightOf="@id/image"
        android:textColor="#e22626"
        style="Custom Notification Title" />
    <TextView android:id="@+id/text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_toRightOf="@id/image"
        android:textColor="#2687e2"
        android:layout_below="@id/title"
        style="Custom Notification Text" />
</RelativeLayout>

Step(2)- MainActivity-
 

public class MainActivity extends AppCompatActivity {


        @SuppressWarnings("deprecation")
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);

            int icon = R.drawable.one;
            long when = System.currentTimeMillis();
            Notification notification = new Notification(icon, "Custom Notification", when);

            NotificationManager mNotificationManager = (NotificationManager)getSystemService(NOTIFICATION_SERVICE);

            RemoteViews contentView = new RemoteViews(getPackageName(), R.layout.activity_main);
            contentView.setImageViewResource(R.id.image, R.drawable.three);
            contentView.setTextViewText(R.id.title, "Custom notification");
            contentView.setTextViewText(R.id.text, "Custom Text");
            notification.contentView = contentView;

            Intent notificationIntent = new Intent(this, MainActivity.class);
            PendingIntent contentIntent = PendingIntent.getActivity(this, 0, notificationIntent, 0);
            notification.contentIntent = contentIntent;

            notification.flags |= Notification.FLAG_NO_CLEAR; //Do not clear the notification
            notification.defaults |= Notification.DEFAULT_LIGHTS; // LED
            notification.defaults |= Notification.DEFAULT_VIBRATE; //Vibration
            notification.defaults |= Notification.DEFAULT_SOUND; // Sound

            mNotificationManager.notify(1, notification);
        }

        @Override
        public boolean onCreateOptionsMenu(Menu menu) {
            getMenuInflater().inflate(R.menu.menu_main, menu);
            return true;
        }
    }