函數式編程應用@FunctionalInterface，λ，LambdaExpress

1. @FunctionalInterface能簡化代碼，解決匿名內部類代碼冗餘，適用單一接口，或被default和static修飾

public interface ObtainxxStatus {
    /**
     * description 獲取進展狀態和節點信息
     *
     * @param sellerId  sellerId
     * @param planCode  planCode
     * @return List<CooperationVO>
     **/
    List<CooperationVO> getxxStatus(Long sellerId,String planCode);

}

2.寫法：拷貝小括號，寫死右箭頭，落地大括號，λ

	ObtainxxStatus cooStatus = (Long sellerIds, String planCodes) -> {
		List<CooperationVO> list = getCooperationList(sellerIds, planCodes);
		if (list != null) {
			return list;
		}
		logger.error("ObtainxxStatus null list");
		return null;
	};