/**
 * 将一组数据平均分成n组
 *
 * @param source 要分组的数据源
 * @param n      平均分成n组
 * @param <T>
 * @return
 */
public static <T> List<List<T>> averageAssign(List<T> source, int n) {
    List<List<T>> result = new ArrayList<List<T>>();
    int remainder = source.size() % n;  //(先计算出余数)
    int number = source.size() / n;  //然后是商
    int offset = 0;//偏移量
    for (int i = 0; i < n; i++) {
        List<T> value = null;
        if (remainder > 0) {
            value = source.subList(i * number + offset, (i + 1) * number + offset + 1);
            remainder--;
            offset++;
        } else {
            value = source.subList(i * number + offset, (i + 1) * number + offset);
        }
        result.add(value);
    }
    return result;
}

/**
 * 将一组数据固定分组，每组n个元素
 * @param source 要分组的数据源
 * @param n      每组n个元素
 * @param <T>
 * @return
 */
public static <T> List<List<T>> fixedGrouping(List<T> source, int n) {

    if (null == source || source.size() == 0 || n <= 0)
        return null;
    List<List<T>> result = new ArrayList<List<T>>();

    int sourceSize = source.size();
    int size = (source.size() / n) + 1;
    for (int i = 0; i < size; i++) {
        List<T> subset = new ArrayList<T>();
        for (int j = i * n; j < (i + 1) * n; j++) {
            if (j < sourceSize) {
                subset.add(source.get(j));
            }
        }
        result.add(subset);
    }
    return result;
}
 

/**
 * 将一组数据固定分组，每组n个元素
 *
 * @param source 要分组的数据源
 * @param n      每组n个元素
 * @param <T>
 * @return
 */
public static <T> List<List<T>> fixedGrouping2(List<T> source, int n) {

    if (null == source || source.size() == 0 || n <= 0)
        return null;
    List<List<T>> result = new ArrayList<List<T>>();
    int remainder = source.size() % n;
    int size = (source.size() / n);
    for (int i = 0; i < size; i++) {
        List<T> subset = null;
        subset = source.subList(i * n, (i + 1) * n);
        result.add(subset);
    }
    if (remainder > 0) {
        List<T> subset = null;
        subset = source.subList(size * n, size * n + remainder);
        result.add(subset);
    }
    return result;
}