FloatingActionButton

MainActivity.java

import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Toast;
 public class MainActivity extends AppCompatActivity {
  FloatingActionButton fabEmail;
  @Override 
   protected void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.activity_main);
   fabEmail = (FloatingActionButton) findViewById(R.id.idFabEmail);
   fabEmail.setOnClickListener(new View.OnClickListener() {
    @Override 
     public void onClick(View view) {
     //Write your Logic Here
     Toast.makeText(getApplicationContext(), "Button Clicked", Toast.LENGTH_SHORT).show();
   }
  });
 }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>  
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:app="http://schemas.android.com/apk/res-auto" 
    xmlns:tools="http://schemas.android.com/tools" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:orientation="vertical" 
     tools:context="arjun.example.com.materialdesign.MainActivity">
    
    <TextView 
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
     android:gravity="center" 
     android:layout_margin="8dp"
     android:text="FloatingActionButton Example"
     android:textSize="18sp"/>
    
    <android.support.design.widget.FloatingActionButton 
     android:id="@+id/idFabEmail" 
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
     android:layout_alignParentBottom="true" 
     android:layout_alignParentRight="true" 
     android:layout_margin="16dp" 
     android:src="@android:drawable/ic_dialog_email" /> 
</RelativeLayout>