Question

listView.setAdapter()正在崩溃我的程序。任何人都知道为什么会发生崩溃？

Logcat错误：

AndroidRuntime﹕ FATAL EXCEPTION: main
    java.lang.NullPointerException

的活动：

public class SavedVideosFragment extends Fragment {
    View rootview;
    MySQLiteHelper mydb;
    private SavedVideoAdapter mSavedVideoAdapter;
    ListView listView;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        rootview = inflater.inflate(R.layout.saved_video_fragment_layout,container,false);

        getSavedVideo();
        listView = (ListView)rootview.findViewById(R.id.savedVideoListView);

        return rootview;
    }

    public void getSavedVideo() {
        mydb = new MySQLiteHelper(getActivity());
        ArrayList savedVideoIDs = mydb.getAllSavedVideo();

        mSavedVideoAdapter = new SavedVideoAdapter(getActivity(), savedVideoIDs, mydb);
        listView.setAdapter(mSavedVideoAdapter);
    }
}

适配器：

public class SavedVideoAdapter extends BaseAdapter {
    private static final int TYPE_ITEM = 0;
    private static final int TYPE_SEPARATOR = 1;

    private ArrayList<Object> mData = new ArrayList<Object>();
    MySQLiteHelper mydb;
    private LayoutInflater mInflater;

    public SavedVideoAdapter(Context context, ArrayList<Object> data, MySQLiteHelper database) {
        mInflater = (LayoutInflater) context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        mData = data;
        mydb = database;
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public int getCount() {
        return mData.size();
    }

    @Override
    public String getItem(int position) {
        Object obj = mData.get(position);
        return "";
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        Cursor res = res = mydb.getData((Integer)mData.get(position));

        convertView =  mInflater.inflate(R.layout.saved_video_adapter, null);
        ImageView imageView = (ImageView) convertView.findViewById(R.id.thumbnail);
        TextView activity = (TextView) convertView.findViewById(R.id.activity);
        TextView activityDate = (TextView) convertView.findViewById(R.id.activityDate);
        ImageView cancel = (ImageView) convertView.findViewById(R.id.x);


        activity.setText(res.getColumnIndex("title"));


        return convertView;
    }
}

ListView XML：

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



    <ListView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/savedVideoListView"
        android:layout_centerHorizontal="true"
        android:layout_alignParentTop="true" />


</RelativeLayout>

适配器布局xml：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="?android:attr/listPreferredItemHeight"
    android:padding="6dip" >

    <ImageView
        android:id="@+id/thumbnail"
        android:layout_width="wrap_content"
        android:layout_height="fill_parent"
        android:layout_alignParentBottom="true"
        android:layout_alignParentTop="true"
        android:layout_marginRight="10dp"
        android:src="@drawable/ic_launcher" />

    <RelativeLayout
        android:layout_width="wrap_content"
        android:layout_height="fill_parent"
        android:layout_toRightOf="@id/thumbnail">
        <TextView
            android:id="@+id/activity"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_alignParentRight="true"
            android:layout_alignParentTop="true"
            android:layout_alignWithParentIfMissing="true"
            android:gravity="center_vertical"
            android:text="Example application"
            android:textSize="16sp" />

        <TextView
            android:id="@+id/activityDate"
            android:layout_width="fill_parent"
            android:layout_height="26dip"
            android:layout_below="@+id/activity"
            android:layout_alignParentBottom="true"
            android:layout_alignParentRight="true"
            android:ellipsize="marquee"
            android:singleLine="true"
            android:text="Description"
            android:textSize="12sp" />

        </RelativeLayout>

    <RelativeLayout
        android:layout_width="?android:attr/listPreferredItemHeight"
        android:layout_height="fill_parent"
        android:layout_alignParentRight="true">
    <ImageView
        android:id="@+id/x"
        android:layout_width="?android:attr/listPreferredItemHeight"
        android:layout_height="?android:attr/listPreferredItemHeight"
        android:layout_alignParentBottom="true"
        android:layout_alignParentTop="true"
        android:layout_marginRight="6dip"
        android:src="@drawable/x" />
</RelativeLayout>

</RelativeLayout>

Answer 1

AndroidRuntime：FATAL EXCEPTION：main java.lang.NullPointerException

因为listView未初始化。

初始化getSavedVideo()后调用listView方法：

listView = (ListView)rootview.findViewById(R.id.savedVideoListView);
getSavedVideo();

listView.setAdapter（）崩溃了我的程序

1 个答案: