de.walware.ecommons.ui.actions.CollapseAllHandler.java Source code

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Here is the source code for de.walware.ecommons.ui.actions.CollapseAllHandler.java

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/*=============================================================================#
 # Copyright (c) 2011-2015 Stephan Wahlbrink (WalWare.de) and others.
 # All rights reserved. This program and the accompanying materials
 # are made available under the terms of the Eclipse Public License v1.0
 # which accompanies this distribution, and is available at
 # http://www.eclipse.org/legal/epl-v10.html
 # 
 # Contributors:
 #     Stephan Wahlbrink - initial API and implementation
 #=============================================================================*/

package de.walware.ecommons.ui.actions;

import org.eclipse.core.commands.AbstractHandler;
import org.eclipse.core.commands.ExecutionEvent;
import org.eclipse.jface.viewers.AbstractTreeViewer;
import org.eclipse.ui.IWorkbenchCommandConstants;

import de.walware.ecommons.ui.util.UIAccess;

/**
 * Handler for command {@link IWorkbenchCommandConstants#NAVIGATE_COLLAPSE_ALL}
 * for a single tree viewer.
 */
public class CollapseAllHandler extends AbstractHandler {

    private AbstractTreeViewer fViewer;

    public CollapseAllHandler(final AbstractTreeViewer viewer) {
        if (viewer == null) {
            throw new NullPointerException("viewer");
        }
        fViewer = viewer;
    }

    @Override
    public void dispose() {
        fViewer = null;
        super.dispose();
    }

    @Override
    public Object execute(final ExecutionEvent event) {
        final AbstractTreeViewer viewer = fViewer;
        if (UIAccess.isOkToUse(viewer)) {
            viewer.collapseAll();
        }
        return null;
    }

}