A filterable ListDataProvider that takes another ListDataProvider for it's source. Handy if you want, say, a CellTable that has a Filter text box. Note that for very large data sets you probably don't want to use this, since it creates a copy of the data each time it applies the filter.

FilteredListDataProvider.java

package app.kiss.client.data;

import java.util.List;

import com.google.common.base.Predicate;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
import com.google.gwt.view.client.HasData;
import com.google.gwt.view.client.ListDataProvider;

public class FilteredListDataProvider<T> extends ListDataProvider<T> {

  public FilteredListDataProvider(ListDataProvider<T> originalProvider) {
		super(originalProvider.getList(), originalProvider.getKeyProvider());
	}

	public Predicate<T> filter;

	public Predicate<T> getFilter() {
		return filter;
	}

	/**
	 * 
	 * @param filter
	 *  
	 *   Example use: 
   *    setFilter(new Predicate<T>() {
	 *                @Override public boolean apply(@Nullable T value) { 
   *                   if (value == null)
	 *                       return false; 
   *                   else return (value.getSomeString().toLowerCase()
	 *                                        .contains(someFilterString)); 
   *                  } });
	 */
	public void setFilter(Predicate<T> filter) {
		if (filter == null)
			resetFilter();
		else {
			this.filter = filter;
			refresh();
		}
	}

	public void resetFilter() {
		filter = null;
		refresh();
	}

	@Override
	protected void updateRowData(HasData<T> display, int start, List<T> values) {
		if (filter != null)
			// apply the filter to the list
			values = Lists.newArrayList(Iterables.filter(values, filter));

		super.updateRowData(display, start, values);

		// need to do this since the filter may have changed the row count
		int size = values.size();
		if (size != display.getRowCount())
			display.setRowCount(size);
	}

	public boolean hasFilter() {
		return filter != null;
	}

}

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