java - Android 新手 - Fragments

Question

Android 编程新手。在过去的三天里，我一直在学习教程，感觉我已经掌握了其中的主要部分。每次我尝试运行以下代码时，android都会导致它在打开之前强制退出。我已经得到了其他更简单的 fragment ，可以毫不费力地工作，但这让我感到困惑。根本没有打印任何错误，可能是因为它立即关闭。任何帮助将不胜感激。

编辑:使用调试器我能够得到一个

 "InflateException: Binary XML file #9: Error inflating class fragment. 

在以下代码之后停止:

 lv = (ListView) view.findViewById(R.id.lvMain);

Frag_MainList.java

public class Frag_MainList extends Fragment implements OnItemClickListener, OnItemLongClickListener{

ListView lv;
ImageView ivAddNote;
Communicator communicator;
Adapter_SQL database = new Adapter_SQL(getActivity());
ArrayList<Element> list; 

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,  Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.frag_mainlist,  container, false);    
    lv = (ListView) view.findViewById(R.id.lvMain);

    database.open();
    list = database.getChildrenLess();
    database.close();

    Adapter_List adapter = new Adapter_List(getActivity(), list);

    lv.setAdapter(adapter);
    lv.setOnItemClickListener(this);
    lv.setOnItemLongClickListener(this);
    return view;
}



@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);

}



@Override
public boolean onItemLongClick(AdapterView<?> arg0, View arg1, int pos, long arg3) {
    communicator.SendID(pos);
    return true;
}


@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int pos, long arg3) {
    database.open();
    database.switchComplete(list.get(pos).id);
    database.close();
}

public void setCommunicator(Communicator communicator){
    this.communicator = communicator;

}

public interface Communicator{
    public void SendID(int index);
}
}

Activity_Main.java

public class Activity_Main extends Activity implements Frag_MainList.Communicator{

Frag_MainList frag1;
Frag_ListChildren frag_children;
FragmentManager manager;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    manager = getFragmentManager(); 
    frag1 = (Frag_MainList) manager.findFragmentById(R.id.fMainList);
    frag1.setCommunicator(this);
}  


@Override
public void SendID(int index) {
     frag_children = (Frag_ListChildren) manager.findFragmentById(R.id.fListChildren);      
     if (frag_children != null && frag_children.isVisible()){
        frag_children.displayChildren(index);
     }else{
         Intent intent = new Intent("com.likwid.wishlist.LISTCHILDREN");
         intent.putExtra("id", index);
         startActivity(intent);
     }    
}
}

frag_mainlist.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >

<ListView
    android:id="@+id/lvMain"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" >
</ListView>

</LinearLayout>

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#00BBFF"
android:orientation="horizontal"
android:id="@+id/main_layout" >

<fragment
    android:id="@+id/fMainList"
    android:name="com.likwid.wishlist.Frag_MainList"
    android:layout_width="wrap_content"
    android:layout_height="match_parent" />

</LinearLayout>

Answer 1

我明白了。看来问题出在数据库上。 Frag_MainList 中的 getActivity 将在 Activity 实际创建之前被调用。将 getActivity 放在“onActivityCreated”方法中可以正确调用 getActivity，并且似乎消除了它引起的所有问题。我认为它显示 fragment 错误的原因是因为 fragment 有缺陷，导致无法膨胀。谢谢大家!