Question

我正在尝试在没有互联网连接时显示空视图没有互联网连接，并且没有找不到书籍时没有显示书籍

这是我的代码

public class MainActivity extends AppCompatActivity {
private static final String BOOK_REQUEST_URL = "https://www.googleapis.com/books/v1/volumes?q=";
public static final String LOG_TAG = MainActivity.class.getName();
// search button
private Button search_button;
// edit text to use for search
private EditText editText;
// string used to get string from edit text.
private String queryWord = null;
private TextView emptyTextView;
private ListView bookListView;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    search_button = (Button) findViewById(R.id.next_button);
    editText = (EditText) findViewById(R.id.edit_text);
    emptyTextView = (TextView) findViewById(R.id.empty_view);

    bookListView = (ListView) findViewById(R.id.list_view);

    // Get a reference to the ConnectivityManager to check state of network connectivity
    ConnectivityManager connMgr = (ConnectivityManager)
            getSystemService(Context.CONNECTIVITY_SERVICE);

    // Get details on the currently active default data network
    final NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();

在这里，我希望什么时候没有连接给我没有互联网连接

 search_button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if (networkInfo != null && networkInfo.isConnected()) {

                new GetBook().execute(BOOK_REQUEST_URL);
            } else {

                emptyTextView.setText(R.string.NoConnect);
                bookListView.setEmptyView(emptyTextView);

            }
        }

    });
    new GetBook().execute(BOOK_REQUEST_URL);
}
//  method to get string from edit text.
public String getBook() {
    queryWord = editText.getText().toString();
    if (queryWord == null) {
        bookListView.setEmptyView(emptyTextView);
    }
    return queryWord;
}

/**
 * Update the UI with the given book information.
 */
private void updateUi(List<Book> books) {

    // Find a reference to the {@link ListView} in the layout

    // Create a new {@link ArrayAdapter} of book
    final BookAdapter adapter = new BookAdapter(this, books);

    // Set the adapter on the {@link ListView}
    // so the list can be populated in the user interface
    bookListView.setAdapter(adapter);

}
// inner class for to support methods do in the background.
private class GetBook extends AsyncTask<String, Void, List<Book>> {

    @Override
    protected List<Book> doInBackground(String... urls) {
        String word_search = getBook();
        // Don't perform the request if there are no URLs, or the first URL is null.
        if (urls.length < 1 || urls[0] == null) {
            return null;
        }
        List<Book> result = QueryUtils.fetchBookName(urls[0], word_search);
        return result;
    }

    /**
     * This method is invoked on the main UI thread after the background work has been
     * completed.
     * <p>
     * It IS okay to modify the UI within this method. We take the {@link Book} object
     * (which was returned from the doInBackground() method) and update the views on the screen.
     */

在这里我想要不显示列表簿

    @Override
        protected void onPostExecute(List<Book> book) {

            emptyTextView.setText(R.string.nobook);
            bookListView.setEmptyView(emptyTextView);

            // Hide loading indicator because the data has been loaded
            View loadingIndicator = findViewById(R.id.loading_indicator);
            loadingIndicator.setVisibility(View.GONE);
            if ((book != null) && !book.isEmpty()) {
                updateUi(book);
            }

        }
    }
}

我尝试了更多的步骤没有发生

Answer 1

试试这个

View  emptyV = getActivity().getLayoutInflater().inflate(R.layout.empty_view, null);
                    TextView tvMSG = (TextView) emptyV.findViewById(R.id.tvMSG);
                    tvMSG.setText("No product available.");
                    ViewGroup viewGroup= (ViewGroup) listView.getParent();                  
                    viewGroup.addView(emptyV, new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
                            ViewGroup.LayoutParams.MATCH_PARENT)); 
                    listView.setEmptyView(emptyV);

Answer 2

您可以为layout状态添加另一个empty，并根据show/hide大小实际list添加<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" xmlns:app="http://schemas.android.com/apk/res-auto" android:id="@+id/container" android:layout_height="match_parent" android:layout_width="match_parent"> <ListView android:id="@+id/list_view" android:layout_width="match_parent" android:layout_height="match_parent" /> <RelativeLayout android:id="@+id/layout_empty" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerVertical="true" android:layout_centerHorizontal="true" android:visibility="gone" android:layout_margin="30dp"> <ImageView android:id="@+id/image_empty" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerHorizontal="true" android:src="@mipmap/ic_launcher"/> <TextView android:id="@+id/text_empty" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerHorizontal="true" android:layout_below="@id/image_empty" android:layout_marginTop="16dp" android:gravity="center" android:textSize="20sp" android:textStyle="bold" android:textColor="@color/textColorPrimary" android:text="Oops!"/> <TextView android:id="@+id/text_empty_hints" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerHorizontal="true" android:layout_below="@id/text_empty" android:layout_marginTop="16dp" android:gravity="center" android:textSize="14sp" android:textStyle="bold" android:textColor="@color/textColorSecondary" android:text="No items found"/> </RelativeLayout> </RelativeLayout>。

以下是一个例子：

<强> activity_main.xml中

private ListView bookListView;
private RelativeLayout layoutEmpty;

.......
............

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

    bookListView = (ListView) findViewById(R.id.list_view);
    layoutEmpty = (RelativeLayout) findViewById(R.id.layout_empty);

    .......
    ...........
}

private void updateUi(List<Book> books) {

    if(books.size() > 0) {
        layoutEmpty.setVisibility(View.GONE);
        bookListView.setVisibility(View.VISIBLE);
    } else {
        layoutEmpty.setVisibility(View.VISIBLE);
        bookListView.setVisibility(View.GONE);
    }
}

<强> MainActivity.java：

The import org.springframework.web.servlet.mvc.AbstractController cannot be resolved

<强>输出：

希望这会有所帮助〜

列表视图中未显示空视图

2 个答案: