从fragmentActivity刷新片段UI

我想从FragmentActivity更改片段中的ImageView(在代码中创建)。(XML中没有片段和标记)。

从FragmentActivity扩展并从GooglePlayServicesClient.ConnectionCallbacks实现的MainActivity:

...
FragmentAdapter mAdapter;
ViewPager mPager;
...

public void onCreate(Bundle savedInstanceState){
    ...
    FragmentManager fm = getSupportFragmentManager();
    mAdapter = new FragmentAdapter(fm);
    mPager.setAdapter(mAdapter);
    ...}

@Override
public void onConnected(Bundle connectionHint){
//*** I want to change a ImageView on Fragment1 here
}

从FragmentPagerAdapter扩展的FragmentAdapter:

...
private FragmentManager mFragmentManager;

public FragmentAdapter(FragmentManager fm){
    super(fm);
}

@Override
public Fragment getItem(int pos){
// String name = makeFragmentName(R.id.mainPager, pos);
// Fragment fragmentObject = mFragmentManager.findFragmentByTag(name);
Fragment fragmentObject = null;

switch(pos){
    case 0:
        fragmentObject = new Fragment1();
        break;
    ...
}

return fragmentObject;
}
...

//private static String makeFragmentName(int viewId, iont index){
    //return "android:switcher:" + viewId + ":" + index;
//}

根据 this 从fragmentActivity更改片段中元素的主题:

片段1从片段:

private ImageView IMGThisImageShouldChange = null;

public View onCreateView(...){
    IMGThisImageShouldChange = (ImageView)v.findViewById(R.id.TargetImage);
    ...
}

public void changeImageView(int resourceId){
    IMGThisImageShouldChange.setImageResource(resouirceId);
}

本主题中的评论行表示:

//不要在每次设置文本时创建新对象。使用相同的 用于查看寻呼机的片段对象。

那么,我如何从MainActivity访问fragmentObject,以调用changeImageView方法?

如果我应该通过标签找到片段,根据 this 主题,我应该在哪里设置标签以及如何查找?