title: Does onDestroy() or finish() actually kill the activity?
body: <p>Actually I know i am asking about the simple and basic concept of Android. But I am a little bit confused about these <code>finish()</code> and <code>onDestroy()</code> methods. 
  Whether this will kill the activity and free the resources associated with these activity?</p>
  
  <p>I tried with a simple application which contains only one activity. I thought  the concept is like When the application runs, the activity will start. and when we click on back button, it will finish. And I gave some toast message inside each life cycle methods for knowing the memory usage . And when I clicked on the back button it executed <code>onPause()</code>, <code>onStop()</code>, and <code>onDestroy()</code>. I thought this activity finished. But when i relaunched the application again, then it took more memory than the previous time. This happens every time when I run the app from eclipse or relaunch the application from home screen.</p>
  
  <p>Why is it happening? How can i actually destroy the application / activity to free the memory?</p>
  
  <hr>
  
  <p>I am including my code. I just give only one toast message inside the class. Then also memory usage is increasing.</p>
  
  <p>Each time when I run the application the allocated size is increasing like : 3302744, 3442384, 3474552</p>
  
  <pre><code> public class myActivity extends Activity
     {
           @Override
           public void onCreate(Bundle savedInstanceState)
           {
               super.onCreate(savedInstanceState);     
          Toast.makeText(getBaseContext()," allocated size  = " + Debug.getNativeHeapAllocatedSize(), 1).show();      
           }
  
     }
  </code></pre>
  
  <p>manifest:</p>
  
  <pre><code>&lt;application android:icon="@drawable/icon" android:label="@string/app_name"&gt;
          &lt;activity android:name=".myActivity "  
                    android:label="@string/app_name"  &gt;
              &lt;intent-filter&gt;
                  &lt;action android:name="android.intent.action.MAIN" /&gt;
                  &lt;category android:name="android.intent.category.LAUNCHER" /&gt;
              &lt;/intent-filter&gt;
          &lt;/activity&gt; 
   &lt;/application&gt;
  </code></pre>
  
  <p>Why is the memory increasing every time?</p>