Question

我的主要目标是使用SearchView中的查询显示（网格）书籍列表（在我的代码中称为BookObjects）。我的代码实际上使用Google Books API从URL解析JSON。我实现的代码修改了searchBox中给定查询的http链接。（它使用ArrayList和自定义适配器以及专为我实现的BookObjects构建的自定义Loader。）

我面临的问题如下：

第一次搜索顺利（gridview从查询字中正确膨胀）但是当我在searchBox中重新键入keyworks时，我的gridView永远不会刷新。它与第一次搜索时的当前项目保持一致。

我在主要活动中的当前代码如下所示：

 public class UserActivity extends AppCompatActivity implements LoaderManager.LoaderCallbacks<List<BookObject>> {
 public String http_link;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_user);
    ...

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.menu_search, menu);
    MenuItem searchItem = menu.findItem(R.id.menuSearch);
    SearchView searchView = (SearchView) searchItem.getActionView();

    final GridView booksListView = (GridView) findViewById(R.id.GridList);
    mEmptyStateTextView = (TextView) findViewById(R.id.empty_view);
    booksListView.setEmptyView(mEmptyStateTextView);

    mAdapter = new BookAdapter(UserActivity.mMainActivity, new ArrayList<BookObject>());
    final LoaderManager loaderManager = getLoaderManager();

    searchView.setOnQueryTextListener(
            new SearchView.OnQueryTextListener() {
                @Override
                public boolean onQueryTextChange(String newText) {

                    return false;
                }

                @Override
                public boolean onQueryTextSubmit(String query) {
                    //check if device is connected to network
                    if (isNetworkConnected() == true) {
                        http_link = "https://www.googleapis.com/books/v1/volumes?q=" + query + "&maxResults=15";

                        Log.d(http_link, "link is:");
                        Log.d(mInputText, "link is:");

                       //Tried them both and had no success
//                           mAdapter.clear();
//                           mAdapter.notifyDataSetChanged();

                        loaderManager.initLoader(BOOK_LOADER_ID, null, UserActivity.mMainActivity);

                        booksListView.setAdapter(mAdapter);


                    } else {
                        mEmptyStateTextView.setText("No internet connection found.");
                    }
                    return false;
                }

            }
    );

    return super.onCreateOptionsMenu(menu);
}


private boolean isNetworkConnected() {
    ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);

    return cm.getActiveNetworkInfo() != null;
}

这些可以在我的自定义BookObject Loader中找到：

（发布它们以便您了解当我调用Loader时会发生什么）

@Override
public Loader<List<BookObject>> onCreateLoader(int i, Bundle bundle) {
    // Create a new loader for the given URL
    return new BookLoader(this, http_link);
}

@Override
public void onLoadFinished(Loader<List<BookObject>> loader, List<BookObject> books) {
    // Clear the adapter of previous earthquake data
    View loadingIndicator = findViewById(R.id.loading_indicator);
    loadingIndicator.setVisibility(View.GONE);

    mAdapter.clear();


    mEmptyStateTextView.setText("No books found");

    // If there is a valid list of {@link BookObject}s, then add them to the adapter's
    // data set. This will trigger the ListView to update.
    if (books != null && !books.isEmpty()) {
        mAdapter.addAll(books);
    }
}

@Override
public void onLoaderReset(Loader<List<BookObject>> loader) {
    // Loader reset, so we can clear out our existing data.
    mAdapter.clear();
}

这是适配器类代码：

public class BookAdapter extends ArrayAdapter<BookObject> {
public BookAdapter(Activity context , List<BookObject> books)
{
    super(context, 0 , books); // 2nd par is 0 because we inflate manually
}

@Override
public View getView(int position , View convertView , ViewGroup parent)
{
    // Check if the existing view is being reused, otherwise inflate the view
    View listItemView = convertView;

    if(listItemView == null) {

        listItemView = LayoutInflater.from(getContext()).inflate(

                R.layout.books_grid_list, parent, false);

    }

    BookObject currentBook = getItem(position);

    TextView TitleTextView = (TextView) listItemView.findViewById(R.id.Title_text_view);
    TitleTextView.setText(currentBook.getTitle());

    TextView SubtitleTextView = (TextView) listItemView.findViewById(R.id.Subtitle_text_view);
    SubtitleTextView.setText(currentBook.getSubtitle());

    TextView AuthorsTextView = (TextView) listItemView.findViewById(R.id.Authors_text_view);
    AuthorsTextView.setText(currentBook.getAuthors());

    ImageView ThumbnailImageView = (ImageView) listItemView.findViewById(R.id.book_image_id);
    Picasso.with(UserActivity.mMainActivity).load(currentBook.getImageURL()).into(ThumbnailImageView);

    return listItemView;
}
}

我在网上搜索了解决方案，我尝试添加onCreateOptionsMenu - ＆gt; onQueryTextSubmit方法不同的行如:(一次一个）

mAdapter.clear();
mAdapter.notifyDataSetChanged();

你能告诉我我错了什么吗？

刷新：我的GridView在第一次查询后永远不会更新。

注意：我通过Logs检查了链接（http_link）是否使用第二个（第3个第4个...等）搜索中的新查询进行了更新。

因此问题在于我的GridView无法使用新项目进行更新。

我真的无法弄明白，任何能引导我走上正确道路的建议都会受到高度赞赏。（现在已经挣扎了5-6个小时）

提前谢谢。

Answer 1

我觉得我发现了问题。它与装载机。从Loader LoaderManager.onInitLoader的文档中，如果已经创建了加载器，那么它只使用相同的加载器并直接调用onLoadFinished()。因此，在onQueryTextSubmit() {而不是致电initLoader()致电restartLoader()

loaderManager.restartLoader(BOOK_LOADER_ID, null, UserActivity.mMainActivity);

GridView无法从SearchView查询中刷新

1 个答案: