javax/swing/DefaultCellEditor.java

/* DefaultCellEditor.java --
   Copyright (C) 2002, 2004, 2006, Free Software Foundation, Inc.

This file is part of GNU Classpath.

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permission to link this library with independent modules to produce an
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package javax.swing;

import java.awt.Component;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.awt.event.MouseEvent;
import java.io.Serializable;
import java.util.EventObject;

import javax.swing.JTable;
import javax.swing.JTextField;
import javax.swing.event.CellEditorListener;
import javax.swing.table.TableCellEditor;
import javax.swing.tree.TreeCellEditor;

/**
 * The default implementation of {@link TableCellEditor} and
 * {@link TreeCellEditor}. It provides editor components for
 * some standard object types.
 *
 * @author Andrew Selkirk
 * @author Audrius Meskauskas
 */
public class DefaultCellEditor
  extends AbstractCellEditor
  implements TableCellEditor, TreeCellEditor
{
  private static final long serialVersionUID = 3564035141373880027L;

  /**
   * This changeable module access the editor component in the component
   * specific way. For instance, to set the value for JTextField, we need to
   * call setText(String), and for JCheckBox we need to call
   * setSelected(boolean). Each default editor has the component specific
   * derivative of this class. These derivatives are private inner classes of
   * the DefaultCellEditor.
   *
   * The editor delegate is also set for the editor component as the action
   * listener. It listens for the events that indicate that editing has stopped.
   */
  protected class EditorDelegate
    implements ActionListener, ItemListener, Serializable
  {
    /**
     * Use the serial version UID for interoperability.
     */
    private static final long serialVersionUID = -1420007406015481933L;

    /**
     * The object value (updated when getting and setting the value).
     */
    protected Object value;

    /**
     * Constructor EditorDelegate
     */
    protected EditorDelegate()
    {
      // Nothing to do here.
    }

    /**
     * Set the value for the editor component. This method is normally
     * overridden to set the value in the way, specific for the text
     * component, check box or combo box.
     *
     * @param aValue the value to set (String, Boolean or Number).
     */
    public void setValue(Object aValue)
    {
      value = aValue;
    }

    /**
     * Get the value for the editor component. This method is normally
     * overridden to obtain the value in the way, specific for the text
     * component, check box or combo box.
     *
     * @return value the value of the component (String, Boolean or Number).
     */
    public Object getCellEditorValue()
    {
      return value;
    }

    /**
     * The default method returns true for the {@link MouseEvent} and false
     * for any other events.
     *
     * @param event the event to check
     *
     * @return true if the passed event is the mouse event and false otherwise.
     */
    public boolean isCellEditable(EventObject event)
    {
      if (event == null || !(event instanceof MouseEvent) ||
          (((MouseEvent) event).getClickCount() >= getClickCountToStart()))
        return true;
      return false;
    } // isCellEditable()

    /**
     * Returns true to indicate that the editing cell can be selected.
     *
     * The default method returns true without action but may be overridden
     * in derived classes for more specific behavior.
     *
     * @param event unused in default method
     *
     * @return true always
     */
    public boolean shouldSelectCell(EventObject event)
    {
      // return true to indicate that the editing cell may be selected
      return true;
    }

    /**
     * Finish the cell editing session. This method notifies the registered
     * cell editor listeners (including the table) that the editing has been
     * stopped.
     *
     * @return boolean
     */
    public boolean stopCellEditing()
    {
      fireEditingStopped();
      return true;
    } // stopCellEditing()

    /**
     * Cancel the cell editing session. This method notifies the registered
     * cell editor listeners (including the table) that the editing has been
     * canceled.
     */
    public void cancelCellEditing()
    {
      fireEditingCanceled();
    } // cancelCellEditing()

    /**
     * Start editing session and returns true to indicate the editing has begun.
     * The default method returns true without action but may be overridden
     * in derived classes for more specific behavior.
     *
     * @param event  the event.
     *
     * @return true, always
     */
    public boolean startCellEditing(EventObject event)
    {
      // return true to indicate that editing has begun
      return true;
    } // startCellEditing()

    /**
     * This event is fired by the editor component (for instance, by pressing
     * ENTER in the {@link JTextField}. The default method delegates call to
     * the {@link #stopCellEditing}, finishing the editing session.
     *
     * @param event unused in default method
     */
    public void actionPerformed(ActionEvent event)
    {
      stopCellEditing();
    } // actionPerformed()

    /**
     * This event is fired by the editor component.The default method delegates
     * call to the {@link #stopCellEditing}, finishing the editing session.
     *
     * @param event unused in default method
     */
    public void itemStateChanged(ItemEvent event)
    {
      stopCellEditing();
    } // itemStateChanged()

    /**
     * Notify the registered listeners (including the table) that the editing
     * has been completed.
     */
    void fireEditingStopped()
    {
      CellEditorListener[] listeners = getCellEditorListeners();
      for (int index = 0; index < listeners.length; index++)
        listeners[index].editingStopped(changeEvent);

    }

    /**
     * Notify the registered listeners (including the table) that the editing
     * has been canceled.
     */
    void fireEditingCanceled()
    {
      CellEditorListener[] listeners = getCellEditorListeners();
      for (int index = 0; index < listeners.length; index++)
        listeners[index].editingCanceled(changeEvent);
    }
  } // EditorDelegate

  /**
   * Provides getter and setter methods to work with the text component.
   *
   * @author Audrius Meskauskas (audriusa@Bioinformatics.org)
   */
  private class JTextFieldDelegate extends EditorDelegate
  {
    /**
     * Use the serial version UID for interoperability.
     */
    private static final long serialVersionUID = 1;

    /**
     * Set the value for the editor component.
     *
     * @param aValue the value to set (toString() will be called).
     */
    public void setValue(Object aValue)
    {
      value = aValue;
      JTextField f = (JTextField) editorComponent;
      if (value == null)
        f.setText("");
      else
        f.setText(value.toString());
    }

    /**
     * Get the value for the editor component.
     *
     * @return value the value of the component (String)
     */
    public Object getCellEditorValue()
    {
      JTextField f = (JTextField) editorComponent;
      return value = f.getText();
    }
  }

  /**
   * Provides getter and setter methods to work with the combo box.
   *
   * @author Audrius Meskauskas (audriusa@Bioinformatics.org)
   */
  private class JComboBoxDelegate extends EditorDelegate
  {
    /**
     * Use the serial version UID for interoperability.
     */
    private static final long serialVersionUID = 1;

    /**
     * Set the value for the editor component.
     *
     * @param aValue the value to set.
     */
    public void setValue(Object aValue)
    {
      value = aValue;
      JComboBox c = (JComboBox) editorComponent;
      if (value != null)
        c.setSelectedItem(value);
    }

    /**
     * Get the value for the editor component.
     *
     * @return value the value of the component (as String)
     */
    public Object getCellEditorValue()
    {
      JComboBox c = (JComboBox) editorComponent;
      return value = c.getSelectedItem();
    }

    /**
     * Returns true to indicate that the editing cell can be selected. If the
     * check box is not editable, expands it. If it is editable, brings
     * focus to the editor field.
     *
     * @param event unused in default method
     *
     * @return true always
     */
    public boolean shouldSelectCell(EventObject event)
    {
      JComboBox c = (JComboBox) editorComponent;
      if (!c.isEditable)
        c.showPopup();
      return true;
    }
  }

  /**
   * Provides getter and setter methods to work with the check box.
   *
   * @author Audrius Meskauskas (audriusa@Bioinformatics.org)
   */
  private class JCheckBoxDelegate extends EditorDelegate
  {
    /**
     * Use the serial version UID for interoperability.
     */
    private static final long serialVersionUID = 1;

    /**
     * Set the value for the editor component.
     *
     * @param value the value to set (must be Boolean).
     */
    public void setValue(Object value)
    {
      JCheckBox c = (JCheckBox) editorComponent;

      if (value == null)
        c.setSelected(false);
      else
        c.setSelected( ((Boolean) value).booleanValue());
    }

    /**
     * Get the value for the editor component.
     *
     * @return value the value of the component (must be CharSequence)
     */
    public Object getCellEditorValue()
    {
      JCheckBox c = (JCheckBox) editorComponent;
      value = c.isSelected() ? Boolean.TRUE : Boolean.FALSE;
      return value;
    }
  }

  /**
   * The Swing JComponent, performing the editing session.
   */
  protected JComponent editorComponent;

  /**
   * The editor delegate, responsible for listening the {@link #editorComponent}
   * events and getting/setting its value.
   */
  protected EditorDelegate delegate;

  /**
   * The number of the mouse clicks, required to start the editing session.
   */
  protected int clickCountToStart;

  /**
   * Create the DefaultCellEditor that uses the text field as its editor
   * component (appropriate for the text content)
   *
   * @param textfield the text field as will be used as the editor component
   */
  public DefaultCellEditor(JTextField textfield)
  {
    editorComponent = textfield;
    clickCountToStart = 2;
    delegate = new JTextFieldDelegate();
    textfield.addActionListener(delegate);
  } // DefaultCellEditor()

  /**
   * Constructor DefaultCellEditor that uses the checkbox (appropriate
   * for boolean values)
   *
   * @param checkbox the checkbox that will be used with this editor.
   */
  public DefaultCellEditor(JCheckBox checkbox)
  {
    editorComponent = checkbox;
    clickCountToStart = 1;
    delegate = new JCheckBoxDelegate();
    checkbox.addActionListener(delegate);
  } // DefaultCellEditor()

  /**
   * Constructor DefaultCellEditor that uses the combo box.
   *
   * @param combobox the combo box that will be used with this editor.
   */
  public DefaultCellEditor(JComboBox combobox)
  {
    editorComponent = combobox;
    clickCountToStart = 1;
    delegate = new JComboBoxDelegate();
    combobox.addActionListener(delegate);
  } // DefaultCellEditor()

  /**
   * Get the component that performs the editing sessions. It is the same
   * component that was passed in constructor.
   *
   * @return the component, performing the editing sessions.
   */
  public Component getComponent()
  {
    return editorComponent;
  } // getComponent()

  /**
   * Get the number of mouse clicks, required to start the editing session.
   *
   * @return int the number of mouse clicks, required to start the session
   */
  public int getClickCountToStart()
  {
    return clickCountToStart;
  } // getClickCountToStart()

  /**
   * Set the number of mouse clicks, required to start the editing session.
   *
   * @param count the number of clicks, required to start the session
   */
  public void setClickCountToStart(int count)
  {
    clickCountToStart = count;
  } // setClickCountToStart()

  /**
   * Get the value, currently being displayed by the editor component. The
   * call is forwarded to the {@link #delegate}.
   *
   * @return Object the value (class depends on the editor component)
   */
  public Object getCellEditorValue()
  {
    return delegate.getCellEditorValue();
  } // getCellEditorValue()

  /**
   * Forwards call to the {@link #delegate}.
   *
   * @param event forwarded to the delegate.
   *
   * @return boolean returned by delegate
   */
  public boolean isCellEditable(EventObject event)
  {
    return delegate.isCellEditable(event);
  } // isCellEditable()

  /**
   * Forwards call to the {@link #delegate}.
   *
   * @param event forwarded to the delegate.
   *
   * @return boolean returned by delegate
   */
  public boolean shouldSelectCell(EventObject event)
  {
    return delegate.shouldSelectCell(event);
  } // shouldSelectCell()

  /**
   * Forwards call to the {@link #delegate}.
   *
   * @return boolean returned by delegate
   */
  public boolean stopCellEditing()
  {
    return delegate.stopCellEditing();
  } // stopCellEditing()

  /**
   * Forwards call to the {@link #delegate}.
   */
  public void cancelCellEditing()
  {
    delegate.cancelCellEditing();
  } // cancelCellEditing()

  /**
   * Sets an initial value for the editor.
   * This will cause the editor to stopEditing and lose any partially
   * edited value if the editor is editing when this method is called.
   * Returns the component that should be added to the client's Component
   * hierarchy. Once installed in the client's hierarchy this component will
   * then be able to draw and receive user input.
   *
   * @param tree - the JTree that is asking the editor to edit; this
   * parameter can be null
   * @param value - the value of the cell to be edited
   * @param isSelected - true is the cell is to be renderer with selection
   * highlighting
   * @param expanded - true if the node is expanded
   * @param leaf - true if the node is a leaf node
   * @param row - the row index of the node being edited
   *
   * @return Component the component for editing
   */
  public Component getTreeCellEditorComponent(JTree tree, Object value,
                                              boolean isSelected,
                                              boolean expanded, boolean leaf,
                                              int row)
  {
    delegate.setValue(value);
    return editorComponent;
  } // getTreeCellEditorComponent()

  /**
   * Get the cell editor component that will perform the editing session. If
   * returned once, the same component is also returned on the repetetive calls
   * again (reused).
   *
   * @param table the table where the editing is performed
   * @param value the current value of the table. It is set as the initial
   *        component value.
   * @param isSelected if true, the cell is currently selected
   * @param row the row of the cell being edited
   * @param column the column of the cell being edited
   *
   * @return Component the component that will perform the editing session
   */
  public Component getTableCellEditorComponent(JTable table, Object value,
                                               boolean isSelected, int row,
                                               int column)
  {
    // NOTE: as specified by Sun, we don't call new() everytime, we return
    // editorComponent on each call to getTableCellEditorComponent or
    // getTreeCellEditorComponent.
    delegate.setValue(value);
    return editorComponent;
  } // getTableCellEditorComponent()

}