android simple notification example

XML (activity_main.xml)

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/rl"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="16dp"
       tools:context=".Notification">

    <Button
        android:id="@+id/btn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:text="Notification" />
</RelativeLayout>

JAVA (MainActivity.java)

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.app.NotificationManager;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.BitmapFactory;
import android.support.v4.app.NotificationCompat;
import android.view.View;
import android.widget.Button;
import android.widget.RelativeLayout;
import android.graphics.Bitmap;

public class Notification extends AppCompatActivity {
    private Context mContext;
    private Resources mResources;
    private RelativeLayout mRelativeLayout;
    private Button mButton;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_notification);

        mContext = getApplicationContext();
        mResources = getResources();
        mRelativeLayout = (RelativeLayout) findViewById(R.id.rl);
        mButton = (Button) findViewById(R.id.btn);
        mButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                NotificationCompat.Builder builder = new NotificationCompat.Builder(mContext);
                builder.setSmallIcon(R.drawable.android);
                Bitmap bitmap = BitmapFactory.decodeResource(mResources, R.drawable.android);
                builder.setLargeIcon(bitmap);
                builder.setContentTitle("Android Studio Pro");
                builder.setContentText("Learn Android App Development");
                int notificationId = 001;
                NotificationManager manager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
                manager.notify(notificationId, builder.build());
            }
        });
    }
}