父活动布局
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".LockerCodeActivity" >
<LinearLayout
android:id="@+id/fragment_container"
android:layout_width="match_parent"
android:layout_height="match_parent">
</LinearLayout>
<ProgressBar
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:id="@+id/ctrlActivityIndicator"
android:indeterminateOnly="true"
android:keepScreenOn="false"
/>
<TextView
android:id="@+id/tv_results"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:text="" />
</RelativeLayout>
在父活动 onCreate 函数中为片段充气
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
Fragment scannerFragment = new ScanFragment();
fragmentTransaction.add(R.id.fragment_container, scannerFragment);
fragmentTransaction.commit();
到目前为止工作得很好......现在我该如何隐藏进度条?这是我尝试过的
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_scan, container, false);
ProgressBar progressBar = (ProgressBar) view.findViewById(R.id.ctrlActivityIndicator);
progressBar.setVisibility(View.INVISIBLE);
return view;
}
我得到一个空指针异常