NullTreeCellEditor.java

/*******************************************************************************
 * Copyright (c) 1998, 2015 Oracle and/or its affiliates. All rights reserved.
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Oracle - initial API and implementation from Oracle TopLink
******************************************************************************/
package org.eclipse.persistence.tools.workbench.uitools.cell;

import java.awt.Component;
import java.util.EventObject;

import javax.swing.JTree;
import javax.swing.event.CellEditorListener;
import javax.swing.tree.TreeCellEditor;

/**
 * Null implementation of TreeCellEditor - useful for
 * nodes that should not be edited.
 *
 * Implemented as a singleton.
 */
public final class NullTreeCellEditor implements TreeCellEditor {

    // singleton
    private static NullTreeCellEditor INSTANCE;

    /**
     * Return the singleton.
     */
    public static synchronized TreeCellEditor instance() {
        if (INSTANCE == null) {
            INSTANCE = new NullTreeCellEditor();
        }
        return INSTANCE;
    }

    /**
     * Ensure non-instantiability.
     */
    private NullTreeCellEditor() {
        super();
    }

    /**
     * @see javax.swing.tree.TreeCellEditor#getTreeCellEditorComponent(javax.swing.JTree, java.lang.Object, boolean, boolean, boolean, int)
     */
    public Component getTreeCellEditorComponent(JTree tree, Object value, boolean isSelected, boolean expanded, boolean leaf, int row) {
        throw new UnsupportedOperationException();
    }

    /**
     * @see javax.swing.CellEditor#cancelCellEditing()
     */
    public void cancelCellEditing() {
        // do nothing
    }

    /**
     * @see javax.swing.CellEditor#stopCellEditing()
     */
    public boolean stopCellEditing() {
        return false;
    }

    /**
     * @see javax.swing.CellEditor#getCellEditorValue()
     */
    public Object getCellEditorValue() {
        return null;
    }

    /**
     * @see javax.swing.CellEditor#isCellEditable(java.util.EventObject)
     */
    public boolean isCellEditable(EventObject anEvent) {
        return false;
    }

    /**
     * @see javax.swing.CellEditor#shouldSelectCell(java.util.EventObject)
     */
    public boolean shouldSelectCell(EventObject anEvent) {
        return false;
    }

    /**
     * @see javax.swing.CellEditor#addCellEditorListener(javax.swing.event.CellEditorListener)
     */
    public void addCellEditorListener(CellEditorListener l) {
        // we don't fire any events, so ignore any listeners
    }

    /**
     * @see javax.swing.CellEditor#removeCellEditorListener(javax.swing.event.CellEditorListener)
     */
    public void removeCellEditorListener(CellEditorListener l) {
        // we don't fire any events, so ignore any listeners
    }

}