getFragmentManager、getSupportFragmentManager和getChildFragmentManager 的區別

jayqiu發表於2018-08-30

使用Fragment需要熟悉幾個類,包括FragmentActivity、FragmentManager、 FragmentTranscation,一個FragmentActivity可以包含多個Fragment,誰來管理?

FragmentManager就起到了作用。做Fragment的增加、刪除、替換的時候,事務FragmentTranslation 來負責執行。

    getFragmentManager()和getSupportFragmentManager()的區別很容易理解,android的v4擴充套件包中的FragmentActivity中獲取FragmentManager使用的就是getSupportFragmentManager(),android.app中獲取管理類的方法就是getFragmentManager()。
複製程式碼

getChildFragmentManager() 屬於 android.support.v4.app.Fragment

    /**
    * Return a private FragmentManager for placing and managing Fragments
    * inside of this Fragment.
    */
   @NonNull
   final public FragmentManager getChildFragmentManager() {
       if (mChildFragmentManager == null) {
           instantiateChildFragmentManager();
           if (mState >= RESUMED) {
               mChildFragmentManager.dispatchResume();
           } else if (mState >= STARTED) {
               mChildFragmentManager.dispatchStart();
           } else if (mState >= ACTIVITY_CREATED) {
               mChildFragmentManager.dispatchActivityCreated();
           } else if (mState >= CREATED) {
               mChildFragmentManager.dispatchCreate();
           }
       }
       return mChildFragmentManager;
   }



  
複製程式碼

getFragmentManager()在Activity中也在 android.support.v4.app.Fragment

 public FragmentManager getFragmentManager() {
        return mFragments.getFragmentManager();
    }
    // android.support.v4.app.Fragment 中
    @Nullable
    final public FragmentManager getFragmentManager() {
        return mFragmentManager;
    }
複製程式碼

getSupportFragmentManager() 在 android.support.v4.app.FragmentActivity

   /**
     * Return the FragmentManager for interacting with fragments associated
     * with this activity.
     */
    public FragmentManager getSupportFragmentManager() {
        return mFragments.getSupportFragmentManager();
    }

複製程式碼