[Managed Bean] Making Primefaces 2.2.RC1 Data Table Filtering works with multiple selection mode.

SomeBean.java

// .. import statements

// ViewScoped is important for AJAX
@ManagedBean
@ViewScoped
public class SomeBean {
  private T[] selectedElementsFromTheList;
  private T[] copyOfSelectedElementsFromTheList;
  private List<T> theList;

  // ... a constructor, get and set methods...

  public T[] getSelectedElementsFromTheList() {
    return copyOfSelectedElementsFromTheList; // don't care about the default.
  }

  public void setSelectedElementsFromTheList(T[] selectedElementsFromTheList) {
    this.selectedElementsFromTheList = selectedElementsFromTheList;
  }

  public List<T> getTheList() {return theList;}

  public void addAnElement(SelectEvent event) {
    int selectedLength = selectedElementsFromTheList.length;
    if (copyOfSelectedElementsFromTheList == null ||
      copyOfSelectedElementsFromTheList.length == 0) {

      copyOfSelectedElementsFromTheList = new T[selectedLength];
      System.arraycopy(selectedElementsFromTheList, 0,
              copyOfSelectedElementsFromTheList, 0, selectedLength);

    } else {
      // event.getObject().getClass() returns the Object type
      T selectedElement = (T) event.getObject();

      T[] temp = copyOfSelectedElementsFromTheList;
      int oldLength = temp.length, newLength = oldLength + 1;
      copyOfSelectedElementsFromTheList = new T[newLength];
      System.arraycopy(temp, 0, copyOfSelectedElementsFromTheList, 0, oldLength);
      copyOfSelectedElementsFromTheList[oldLength] = selectedElement;
    }
  }

  public void removeAnElement(UnselectEvent event) {
    T unselectedElement = (T) event.getObject();
    int numBackups = copyOfSelectedElementsFromTheList.length;
    for (int i = 0; i < numBackups; ++i) {
      if (copyOfSelectedElementsFromTheList[i].getId() ==
        unselectedElement.getId()) {
        numBackups--;
        T[] temp = copyOfSelectedElementsFromTheList;
        copyOfSelectedElementsFromTheList = new T[numBackups];
        System.arraycopy(temp, 0, copyOfSelectedElementsFromTheList, 0, i);
        System.arraycopy(temp, i + 1, copyOfSelectedElementsFromTheList, i, numBackups - i);
        break;
      }
    }
  }
}