DialogFragment can be used as Dialog as well as embedded inside Acitivity's view hierarchy.

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.test.MainActivity"
    tools:ignore="MergeRootFrame">
    
	<Button
	    android:id="@+id/button1"
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:text="Dialog"
	    android:onClick="launchDialog"
	    android:layout_alignParentTop="true" />
		
	<Button
	    android:id="@+id/button2"
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:text="Embed"
	    android:onClick="embedDialog"
	    android:layout_below="@id/button1" />

	<FrameLayout
	    android:id="@+id/fragmentContainer"
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:layout_below="@id/button2" />
	
</RelativeLayout>

fragment_main.xml

<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="com.example.test.MainActivity$PlaceholderFragment" >

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</RelativeLayout>

MainActivity.java

package com.example.test;

import android.app.Activity;
import android.app.DialogFragment;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

public class MainActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
	}
	
	public void launchDialog(View v) {
		MyDialog dialog = new MyDialog();
		dialog.show(this.getFragmentManager(), "mydialog");
	}
	
	public void embedDialog(View v) {
		FragmentTransaction ft = this.getFragmentManager().beginTransaction();
		MyDialog dialog = new MyDialog();
		ft.add(R.id.fragmentContainer, dialog);
		ft.commit();
	}
	
	public static class MyDialog extends DialogFragment {
		
		public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
			View v = inflater.inflate(R.layout.fragment_main, container, false);
			if(getDialog() != null) // For embedded views this is null
				getDialog().setTitle("Shown as Dialog");
			
			TextView tv = (TextView) v.findViewById(R.id.textView);
			tv.setText("This is a dialog");
			return v;
		}
	}
}