<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >

<ImageButton
    android:id="@+id/imageButton1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignRight="@+id/textView1"
    android:layout_below="@+id/textView1"
    android:layout_marginRight="35dp"
    android:layout_marginTop="32dp"
    android:contentDescription="image"
    android:src="@drawable/ic_launcher" />

import android.app.Activity;
 import android.os.Bundle;
 import android.view.Menu;
 import android.view.View;
 import android.view.View.OnClickListener;
 import android.widget.ImageButton;
 import android.widget.Toast;

 public class MainActivity extends Activity {

ImageButton imgButton;

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

    addListenerOnButton();
}

private void addListenerOnButton() {

    imgButton = (ImageButton) findViewById(R.id.imageButton1);

    imgButton.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View view) {
            Toast.makeText(MainActivity.this, "Clicked", Toast.LENGTH_SHORT)
                    .show();
        }
    });
}
}

import android.widget.Toast;

    public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.your_main_xml_here, container, false);
            rootView.findViewById(R.id.user_button_ratings).setOnClickListener(
                    new View.OnClickListener() {
                        @Override
                        public void onClick(View v) {
                        Toast.makeText(getActivity(),
                                    "Button was clicked", Toast.LENGTH_SHORT).show();

                    }
            });

     return rootView;
     }