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 Summary

Constructors

Modifier	Constructor and Description
protected	AsyncDataProvider() Constructs an AsyncDataProvider without a key provider.
protected	AsyncDataProvider(ProvidesKey<T> keyProvider) Constructs an AsyncDataProvider with the given key provider.

Method Summary

Modifier and Type	Method and Description
void	updateRowCount(int size, boolean exact) Inform the displays of the total number of items that are available.
void	updateRowData(int start, java.util.List<T> values) Inform the displays of the new data.

Methods inherited from class com.google.gwt.view.client.AbstractDataProvider

addDataDisplay, getDataDisplays, getKey, getKeyProvider, getRanges, onRangeChanged, removeDataDisplay, updateRowData

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

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 Detail

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,
                          java.util.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