CollectionUtil.java

/**
 * Copyright 2008 The University of North Carolina at Chapel Hill
 *
 * Licensed 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 edu.unc.lib.dl.ui.util;

import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.Iterator;

public class CollectionUtil {

	public static boolean contains(Collection<?> coll, Object target){
		if (coll == null)
			return false;
		return coll.contains(target);
	}
	
	public static List<?> subList(List<?> list, int fromIndex, int toIndex) {
		return list.subList(fromIndex, toIndex);
	}
	
	public static String joinLookup(Iterable<?> elements, String separator, Map<?,?> lookup){
		if (elements == null)
			return "";
		StringBuilder buf = new StringBuilder();
		if (separator == null)
			separator = " ";
		
		for (Object o: elements) {
			if (buf.length() > 0)
				buf.append(separator);
			buf.append(lookup.get(o));
		}
		return buf.toString();
	}
	
	public static String join(Iterable<?> elements, String separator){
		if (elements == null)
			return "";
		StringBuilder buf = new StringBuilder();
		if (separator == null)
			separator = " ";
		
		for (Object o: elements) {
			if (buf.length() > 0)
				buf.append(separator);
			buf.append(o);
		}
		return buf.toString();
	}
	
	public static String join(Map<?,?> elements, String keySeparator, String entrySeparator){
		if (elements == null)
			return "";
		StringBuilder buf = new StringBuilder();
		if (keySeparator == null)
			keySeparator = " ";
		if (entrySeparator == null)
			entrySeparator = " ";
		
		Iterator<?> elementsIt = elements.entrySet().iterator();
		while (elementsIt.hasNext()){
			if (buf.length() > 0)
				buf.append(entrySeparator);
			Map.Entry<?, ?> element = (Map.Entry<?, ?>)elementsIt.next();
			buf.append(element.getKey()).append(keySeparator).append(element.getValue());
		}
		return buf.toString();
	}
	
	public static void decrementLongMap(Map<String,Long> map, String key){
		if (!map.containsKey(key))
			return;
		map.put(key, map.get(key) - 1);
	}
}