apache commons-collections BagUtils

import java.util.Iterator;

import org.apache.commons.collections.Bag;
import org.apache.commons.collections.BagUtils;
import org.apache.commons.collections.bag.HashBag;
public class BagCounter{
	
	public static void main(String[] args){
		String[] testArray={"java core","think in java","spring in action",
				"java hibernate","hibernate in action"};
		Bag bag=createBag(testArray);
		printBag(bag);
	}
	
	private static Bag createBag(String[] strArray){
		if(strArray==null||strArray.length==0){
			return BagUtils.EMPTY_BAG;
		}
		Bag bag=new HashBag();
		for(int i=0;i<strArray.length;i++){
			String[] tagArray=strArray[i].split(" ");
			for(int j=0;j<tagArray.length;j++){
				bag.add(tagArray[j]);
			}
		}
		return bag;
	}
	private static void printBag(Bag bag){
		for(Iterator i=bag.uniqueSet().iterator();i.hasNext();){
			String tag=(String)i.next();
			int count=bag.getCount(tag); 
			System.out.println(tag+" ( "+count+")");
		}
	}
}