[Android]Activity vs FragmentActivity?

extends Activity ? or extands FragmentActivity?

issue

如果我開發版本是4.X以上
import android.app.Fragment;
是沒問題的

但如果我要加上+viewpaper
它的import就是import android.support.v4.view.ViewPager;
這樣我fragment就要改成import android.support.v4.app.Fragment;
不然會有錯

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Soulation

Support android.app classes to assist with development of applications for android API level 4 or later.

所以如果要使用viewpaper就要選擇 import android.support.v4.view.ViewPager
並配合FragmentActivity來切換頁面

public class MainActivity extends Activity // above 3.0
public class MainActivity extends FragmentActivity // below 3.0

FragmentActivity
FragmentActivity is a subclass of Activity that was built for the Android Support Package. Here

Import
Also remember use Activity if you are using android.app.Fragment; use FragmentActivity if you are usingandroid.support.v4.app.Fragment. Here

所以說到目前為止我的觀念是
如果要使用Viewpaper就一定會extends FragmentActivity來切換頁面
也就是說一定會用到Support v4了

觀念有錯，麻煩指教
有新的觀念在來修正

Ref:
Android Fragment Activity