adb shell에서 특정 activity실행하기

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
 package="com.iftitah.android.contact">
  <application android:icon="@drawable/icon">
   <activity class=".Contact" android:label="@string/app_name">
    <intent-filter>
    <action android:value="android.intent.action.MAIN" />
    <category android:value="android.intent.category.LAUNCHER" />
   </intent-filter>
  </activity>
 </application>
.
.
</manifest>

위와 같이 activity가 정의되어 있을 때... 아래와 같이 실행하면 됨

am start -a android.intent.action.MAIN -n
com.iftitah.android.contact/com.iftitah.android.contact.Contact