CollectionTools.java

package com.firefly.utils.lang;

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public abstract class CollectionTools {

	public static <F,S,T> Map<F, S> transform(Collection<T> from, MultiReturnFunction<F, S, T> function) {
		if(from == null || from.size() == 0)
			return null;
		
		Map<F, S> map = new HashMap<F, S>();
		for(T t : from) {
			Pair<F, S> pair = function.apply(t);
			map.put(pair.first, pair.second);
		}
		return map;
	}
	
	public static <F, T> List<F> transform(Collection<T> from, SingleReturnFunction<F, T> function) {
		if(from == null || from.size() == 0)
			return null;
		
		List<F> collection = new ArrayList<F>();
		for(T t : from) {
			collection.add(function.apply(t));
		}
		return collection;
	}
}