AbstractEditableCell (GWT Javadoc)

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## com.google.gwt.cell.client
Class AbstractEditableCell<C,V>

    java.lang.Object
      com.google.gwt.cell.client.AbstractCell<C>
          com.google.gwt.cell.client.AbstractEditableCell<C,V>

Type Parameters:
  `C` - the type that this Cell represents
  `V` - the data type of the view data state

All Implemented Interfaces:
  Cell<C>

Direct Known Subclasses:
  AbstractInputCell, CheckboxCell, DatePickerCell, EditTextCell

    public abstract class AbstractEditableCell<C,V>

extends AbstractCell<C>

A default implementation of the `Cell` interface used for editable cells that need to save view data state for specific values.

### Example

>     public class EditableCellExample implements EntryPoint {

>       /**
>        * A simple data type that represents a contact.
>        */
>       private static class Contact {
>         private final String address;
>         private final String name;

>         public Contact(String name, String address) {
>           this.name = name;
>           this.address = address;
>         }
>       }

>       /**
>        * A custom {@link Cell} used to render a {@link Contact}. We extend
>        * {@link AbstractCell} because it provides reasonable implementations of
>        * methods that work for most use cases.
>        */
>       private class ContactCell extends AbstractCell<Contact> {

>         public ContactCell() {
>           // Our cell responds to change events and keydown events.
>           super("change", "keydown");
>         }

>         @Override
>         public void onBrowserEvent(Context context, Element parent, Contact value,
>             NativeEvent event, ValueUpdater<Contact> valueUpdater) {
>           // Check that the value is not null.
>           if (value == null) {
>             return;
>           }

>           // Call the super handler, which handlers the enter key.
>           super.onBrowserEvent(context, parent, value, event, valueUpdater);

>           // Handle click events.
>           if ("change".equals(event.getType())) {
>             updateFavorites(parent, value);
>             showCurrentFavorites();
>           }
>         }

>         @Override
>         public void render(Context context, Contact value, SafeHtmlBuilder sb) {
>           /*
>            * Always do a null check on the value. Cell widgets can pass null to
>            * cells if the underlying data contains a null, or if the data arrives
>            * out of order.
>            */
>           if (value == null) {
>             return;
>           }

>           // Add a checkbox. If the contact is a favorite, the box will be checked.
>           sb.appendHtmlConstant("<table><tr><td valign=\"top\">");
>           if (favorites.contains(value)) {
>             sb.appendHtmlConstant("<input type=\"checkbox\" checked=checked/>");
>           } else {
>             sb.appendHtmlConstant("<input type=\"checkbox\" />");
>           }
>           sb.appendHtmlConstant("</td><td>");

>           // Display the name in big letters.
>           sb.appendHtmlConstant("<div style=\"size:200%;font-weight:bold;\">");
>           sb.appendEscaped(value.name);
>           sb.appendHtmlConstant("</div>");

>           // Display the address in normal text.
>           sb.appendHtmlConstant("<div style=\"padding-left:10px;\">");
>           sb.appendEscaped(value.address);
>           sb.appendHtmlConstant("</div>");

>           sb.appendHtmlConstant("</td></tr></table>");
>         }

>         /**
>          * By convention, cells that respond to user events should handle the enter
>          * key. This provides a consistent user experience when users use keyboard
>          * navigation in the widget. Our cell will toggle the checkbox on Enter.
>          */
>         @Override
>         protected void onEnterKeyDown(Context context, Element parent,
>             Contact value, NativeEvent event, ValueUpdater<Contact> valueUpdater) {
>           // Toggle the checkbox.
>           InputElement input = getInputElement(parent);
>           input.setChecked(!input.isChecked());

>           // Update the favorites based on the new state.
>           updateFavorites(parent, value);

>           // Show the new list of favorites.
>           showCurrentFavorites();
>         }

>         /**
>          * Get the checkbox input element from the parent element that wraps our
>          * cell.
>          *
>          * @param parent the parent element
>          * @return the checkbox
>          */
>         private InputElement getInputElement(Element parent) {
>           // We need to navigate down to our input element.
>           TableElement table = parent.getFirstChildElement().cast();
>           TableRowElement tr = table.getRows().getItem(0);
>           TableCellElement td = tr.getCells().getItem(0);
>           InputElement input = td.getFirstChildElement().cast();
>           return input;
>         }

>         /**
>          * Update the favorites list based on the state of the input element.
>          */
>         private void updateFavorites(Element parent, Contact value) {
>           // Get the input element.
>           InputElement input = getInputElement(parent);

>           // Update the favorites based on the checked state.
>           if (input.isChecked()) {
>             favorites.add(value);
>           } else {
>             favorites.remove(value);
>           }
>         }
>       }

>       /**
>        * The list of data to display.
>        */
>       private static final List<Contact> CONTACTS = Arrays.asList(new Contact(
>           "John", "123 Fourth Avenue"), new Contact("Joe", "22 Lance Ln"),
>           new Contact("Michael", "1283 Berry Blvd"), new Contact("Sarah",
>               "100 Hundred St."), new Contact("George", "1600 Pennsylvania Avenue"));

>       /**
>        * Our list of favorite contacts.
>        */
>       private final List<Contact> favorites = new ArrayList<EditableCellExample.Contact>();

>       public void onModuleLoad() {
>         // Create a cell to render each value.
>         ContactCell contactCell = new ContactCell();

>         // Use the cell in a CellList.
>         CellList<Contact> cellList = new CellList<Contact>(contactCell);

>         // Push the data into the widget.
>         cellList.setRowData(0, CONTACTS);

>         // Add it to the root panel.
>         RootPanel.get().add(cellList);
>       }

>       /**
>        * Show the list of favorites.
>        */
>       private void showCurrentFavorites() {
>         if (favorites.size() > 0) {
>           String text = "You favorite contacts are ";
>           boolean first = true;
>           for (Contact contact : favorites) {
>             if (!first) {
>               text += ", ";
>             } else {
>               first = false;
>             }
>             text += contact.name;
>           }
>           Window.alert(text);
>         } else {
>           Window.alert("You have not selected any favorites.");
>         }
>       }
>     }

Nested Class Summary

Nested classes/interfaces inherited from interface com.google.gwt.cell.client.Cell
`Cell.Context`

Constructor Summary
`AbstractEditableCell(java.util.Set<java.lang.String> consumedEvents)` Construct a new `AbstractEditableCell` with the specified consumed events.
`AbstractEditableCell(java.lang.String... consumedEvents)` Construct a new `AbstractEditableCell` with the specified consumed events.

Method Summary
`void` | `clearViewData(java.lang.Object key)` Clear the view data associated with the specified key.
`V` | `getViewData(java.lang.Object key)` Get the view data associated with the specified key.
`abstract boolean` | `isEditing(Cell.Context context, Element parent, C value)` Returns true if the cell is currently editing the data identified by the given element and key.
`void` | `setViewData(java.lang.Object key, V viewData)` Associate view data with the specified key.

Methods inherited from class com.google.gwt.cell.client.AbstractCell
`dependsOnSelection, getConsumedEvents, handlesSelection, onBrowserEvent, onEnterKeyDown, render, resetFocus, setValue`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### AbstractEditableCell

    public AbstractEditableCell(java.lang.String... consumedEvents)

  Construct a new `AbstractEditableCell` with the specified consumed events.

  Parameters:
    `consumedEvents` - the events that this cell consumes

### AbstractEditableCell

    public AbstractEditableCell(java.util.Set<java.lang.String> consumedEvents)

  Construct a new `AbstractEditableCell` with the specified consumed events.

  Parameters:
    `consumedEvents` - the events that this cell consumes

Method Detail

### clearViewData

    public void clearViewData(java.lang.Object key)

  Clear the view data associated with the specified key.

  Parameters:
    `key` - the key identifying the row value

### getViewData

    public V getViewData(java.lang.Object key)

  Get the view data associated with the specified key.

  Parameters:
    `key` - the key identifying the row object
  Returns:
    the view data, or null if none has been set
  See Also:
    `setViewData(Object, Object)`

### isEditing

    public abstract boolean isEditing(Cell.Context context,
                                      Element parent,
                                      C value)

  Returns true if the cell is currently editing the data identified by the given element and key. While a cell is editing, widgets containing the cell may choose to pass keystrokes directly to the cell rather than using them for navigation purposes.

  Specified by:
    `isEditing` in interface `Cell<C>`
  Overrides:
    `isEditing` in class `AbstractCell<C>`
  Parameters:
    `context` - the `Context` of the cell
    `parent` - the parent Element
    `value` - the value associated with the cell
  Returns:
    true if the cell is in edit mode

### setViewData

    public void setViewData(java.lang.Object key,
                            V viewData)

  Associate view data with the specified key. If the key is null, the view data will be ignored.

  Parameters:
    `key` - the key of the view data
    `viewData` - the view data to associate
  See Also:
    `getViewData(Object)`

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