Package com.google.gwt.view.client

Class AsyncDataProvider<T>

java.lang.Object
com.google.gwt.view.client.AbstractDataProvider<T>
com.google.gwt.view.client.AsyncDataProvider<T>
Type Parameters:
T - the data type of records in the list
All Implemented Interfaces:
ProvidesKey<T>
public abstract class AsyncDataProvider<T> extends AbstractDataProvider<T>
An implementation of AbstractDataProvider that allows the data to be modified.

Example

public class AsyncDataProviderExample implements EntryPoint {

  /**
   * A custom {@link AsyncDataProvider}.
   */
  private static class MyDataProvider extends AsyncDataProvider<String> {
    /**
     * {@link #onRangeChanged(HasData)} is called when the table requests a new
     * range of data. You can push data back to the displays using
     * {@link #updateRowData(int, List)}.
     */
    @Override
    protected void onRangeChanged(HasData<String> display) {
      // Get the new range.
      final Range range = display.getVisibleRange();

      /*
       * Query the data asynchronously. If you are using a database, you can
       * make an RPC call here. We'll use a Timer to simulate a delay.
       */
      new Timer() {
        @Override
        public void run() {
          // We are creating fake data. Normally, the data will come from a
          // server.
          int start = range.getStart();
          int length = range.getLength();
          List<String> newData = new ArrayList<String>();
          for (int i = start; i < start + length; i++) {
            newData.add("Item " + i);
          }

          // Push the data to the displays. AsyncDataProvider will only update
          // displays that are within range of the data.
          updateRowData(start, newData);
        }
      }.schedule(3000);
    }
  }

  public void onModuleLoad() {
    // Create a CellList.
    CellList<String> cellList = new CellList<String>(new TextCell());

    // Create a data provider.
    MyDataProvider dataProvider = new MyDataProvider();

    // Add the cellList to the dataProvider.
    dataProvider.addDataDisplay(cellList);

    // Create paging controls.
    SimplePager pager = new SimplePager();
    pager.setDisplay(cellList);

    // Add the widgets to the root panel.
    VerticalPanel vPanel = new VerticalPanel();
    vPanel.add(pager);
    vPanel.add(cellList);
    RootPanel.get().add(vPanel);
  }
}

  • Constructor Details

    • AsyncDataProvider

      protected AsyncDataProvider()
      Constructs an AsyncDataProvider without a key provider.

    • AsyncDataProvider

      protected AsyncDataProvider(ProvidesKey<T> keyProvider)
      Constructs an AsyncDataProvider with the given key provider.
      Parameters:
      keyProvider - an instance of ProvidesKey, or null if the record object should act as its own key

  • Method Details

    • updateRowCount

      public void updateRowCount(int size, boolean exact)
      Description copied from class: AbstractDataProvider
      Inform the displays of the total number of items that are available.
      Overrides:
      updateRowCount in class AbstractDataProvider<T>
      Parameters:
      size - the new total row count
      exact - true if the count is exact, false if it is an estimate

    • updateRowData

      public void updateRowData(int start, List<T> values)
      Description copied from class: AbstractDataProvider
      Inform the displays of the new data.
      Overrides:
      updateRowData in class AbstractDataProvider<T>
      Parameters:
      start - the start index
      values - the data values