Data grouping summary

Divide a set of data into n groups on average

 /**
     * 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;
    }

Group a set of data fixedly, each group of n elements is divided into multiple groups

 /**
     * 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;
    }