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Ant example source code file (Union.java)

This example Ant source code file (Union.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Ant tags/keywords

arraylist, baseresourcecollectioncontainer, collection, collection, iterator, list, object, resource, resource, resourcecollection, string, string, union, union, util

The Union.java source code

/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 */
package org.apache.tools.ant.types.resources;

import java.util.List;
import java.util.Iterator;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;

import org.apache.tools.ant.types.Resource;
import org.apache.tools.ant.types.ResourceCollection;

/**
 * ResourceCollection representing the union of multiple nested ResourceCollections.
 * @since Ant 1.7
 */
public class Union extends BaseResourceCollectionContainer {

    /**
     * Static convenience method to union an arbitrary set of Resources.
     * @param rc a ResourceCollection.
     * @return a Union.
     */
    public static Union getInstance(ResourceCollection rc) {
        return rc instanceof Union ? (Union) rc : new Union(rc);
    }

    /**
     * Default constructor.
     */
    public Union() {
    }

    /**
     * Convenience constructor.
     * @param rc the ResourceCollection to add.
     */
    public Union(ResourceCollection rc) {
        add(rc);
    }

    /**
     * Returns all Resources in String format. Provided for
     * convenience in implementing Path.
     * @return String array of Resources.
     */
    public String[] list() {
        if (isReference()) {
            return ((Union) getCheckedRef()).list();
        }
        Collection result = getCollection(true);
        return (String[]) (result.toArray(new String[result.size()]));
    }

    /**
     * Convenience method.
     * @return Resource[]
     */
    public Resource[] listResources() {
        if (isReference()) {
            return ((Union) getCheckedRef()).listResources();
        }
        Collection result = getCollection();
        return (Resource[]) (result.toArray(new Resource[result.size()]));
    }

    /**
     * Unify the contained Resources.
     * @return a Collection of Resources.
     */
    protected Collection getCollection() {
        return getCollection(false);
    }

    /**
     * Unify the contained Resources.
     * @param asString indicates whether the resulting Collection
     *        should contain Strings instead of Resources.
     * @return a Collection of Resources.
     */
    protected Collection getCollection(boolean asString) {
        List rc = getResourceCollections();
        if (rc.isEmpty()) {
            return Collections.EMPTY_LIST;
        }
        //preserve order-encountered using a list; enforce set logic manually:
        ArrayList union = new ArrayList(rc.size() * 2);
        for (Iterator rcIter = rc.iterator(); rcIter.hasNext();) {
            for (Iterator r = nextRC(rcIter).iterator(); r.hasNext();) {
                Object o = r.next();
                if (asString) {
                    o = o.toString();
                }
                if (!(union.contains(o))) {
                    union.add(o);
                }
            }
        }
        return union;
    }

    private static ResourceCollection nextRC(Iterator i) {
        return (ResourceCollection) i.next();
    }
}

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