列表异同；列表不同部分；

• 业务有用到,然后参考了归并排序写了这个工具

适合大数据量,因为不需要map辅助,省内存,入参只能是两个已经去重的列表,然后可以得到两个列表独有以及共有的部分

/**
 * 列表异同 , 参考了归并排序
 */
@Data
@NoArgsConstructor
@AllArgsConstructor
public class DiffBetweenTwoList<T> {

    /**
     * 左边独有
     */
    List<T> leftOnly;
    /**
     * 共有
     */
    List<T> comm;
    /**
     * 右边独有
     */
    List<T> rightOnly;

    /**
     * 大数据量用这个省内存
     *
     * @param left       左
     * @param right      右
     * @param comparator 比较器
     * @return {@link Map}<{@link Integer}, {@link List}<{@link T}>>
     */
    public static <T> DiffBetweenTwoList<T> getDiffFromTwoList(List<T> left, List<T> right, Comparator<T> comparator) {

        DiffBetweenTwoList<T> res = new DiffBetweenTwoList<>();

        List<T> onlyLeft = new ArrayList<>();
        List<T> onlyRight = new ArrayList<>();
        List<T> equals = new ArrayList<>();

        left.sort(comparator);
        right.sort(comparator);

        int leftSize = left.size();
        int rightSize = right.size();

        int i = 0, j = 0;
        while (i < leftSize || j < rightSize) {

            if (j >= rightSize) {
                while (i < leftSize) {
                    onlyLeft.add(left.get(i));
                    i++;
                }
            }
            if (i >= leftSize) {
                while (j < rightSize) {
                    onlyRight.add(right.get(j));
                    j++;
                }
            }

            while (i < leftSize && comparator.compare(left.get(i), right.get(j)) < 0) {
                onlyLeft.add(left.get(i));
                i++;
            }

            while (i < leftSize && j < rightSize && comparator.compare(left.get(i), right.get(j)) > 0) {
                onlyRight.add(right.get(j));
                j++;
            }

            while (i < leftSize && j < rightSize && comparator.compare(left.get(i), right.get(j)) == 0) {
                equals.add(left.get(i));
                i++;
                j++;
            }
        }

        res.setLeftOnly(onlyLeft);
        res.setComm(equals);
        res.setRightOnly(onlyRight);
        return res;
    }

}