平时开发的优化代码：

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The provided content covers various aspects of checking for null values and handling different scenarios: **1. Checking for null:** * `Objects.requireNonNull(contactId)` throws an `IllegalArgumentException` if `contactId` is null. * `List.of("a", "a", "a").stream().allMatch(Objects::nonNull)` checks if all elements in the list are not null. **2. Handling multiple conditions:** * `if(Stream.of(InProgress, Queued).anyMatch(status -> Objects.equals(source.getStatusCd(), status))}` checks if the order is in either "InProgress" or "Queued" status. * `if(Arrays.asList(dailyLimit, monthLimit).contains(type)){}` checks if the specified type is within the allowed range. **3. Handling null values:** * `Optional.ofNullable(source.getOrigPoints()).map(BigDecimal::valueOf).orElse(null)` handles null values by converting them to a `BigDecimal` object. * `memTier.setSeqNum(Objects.requireNonNullElse(tier, Tier::new).getSeqNum());` sets the `seqNum` field to the default value if it's null. **4. JSON parsing:** * `String segmentNo = json.optString("SegmentNo")` retrieves the `SegmentNo` from the JSON string. * `String partnerFlag = customerJson.opt("PartnerFlag")` retrieves the `PartnerFlag` from the JSON object. **5. Conditional logic:** * `Optional.ofNullable(memberSegment) .map(existingSegment -> {...}` checks if a member segment already exists and updates it if it does. * `if (isRepeatedOrder.test(posConfirmPointVO)) { handleRepeatedOrder.run(); } else { handleNonRepeatedOrder.run(); }` executes different logic based on whether the order is repeated. **6. Stream operations for handling nulls:** * `Stream.of(apolloServiceConfig.parseItemUrl(), isUpdateBlue ? apolloServiceConfig.parseBlueItemUrl() : Stream.empty())` loads configuration URLs based on the `isUpdateBlue` flag. **7. Stream lambda expression:** * `Optional.ofNullable(posConfirmReqVO.getAccounts()) .filter(accounts -> !accounts.isEmpty()) .flatMap(accounts -> accounts.stream() .filter(acc -> \"1000\".equals(acc.getId())) .findFirst()) .ifPresent(x -> posConfirmReqVO.setAccount1000Value(x.getEarnValue()))` updates the `account1000` value with the first non-empty account's earning. **8. Optimizing conditional checks:** * The new code uses an `if`-`else` block for improved readability and avoids the need for separate `if` conditions. **9. Jdk9 optimization:** * The code uses lambda expressions and `Stream` operations for improved readability and performance. **10. Stream optimization:** * The new code uses `Optional` to handle null values and returns the relevant object or a default value.

正文

第一：检验，报错直接抛出异常： Objects.requireNonNull(contactId);

第二：方法名，检查是否需要输出日志： if(printLogIfNeeded) 　　//对于sql查询方法、java中的方法名字的命名定义推荐: find..By/query..By/get..By

// 检验查询结果是否 业务需要返回的code
CustomerBuPO customerBu = Optional.ofNullable(foundationRepository.getBuByName(reqVO.getBuId()))
           .orElseThrow(() -> new BusinessException(101, "buId not exist"));

第三：三个字段都不为null的情况下执行的代码；

if (List.of("a", "a", "a").stream().allMatch(Objects::nonNull)) {
    System.out.println("3个对象都不为空");
}

第四：其中有2个条件任一匹配到：

　　 if(Stream.of(InProgress, Queued).anyMatch(status -> Objects.equals(source.getStatusCd(), status))){ }

或者：if(Arrays.asList(dailyLimit, monthLimit).contains(type)){}

或者：StringUtils.equalsAny(a,b,c)  //只要有一个不为空

第五：如果为null值，但是要转换字段类型取值，都可以用这种方法：

CustomerLoyTxnStg loyTxnStg = new CustomerLoyTxnStg();
loyTxnStg.setOrigPoints(Optional.ofNullable(source.getOrigPoints()).map(BigDecimal::valueOf).orElse(null));
或者：
memTier.setSeqNum(Objects.requireNonNullElse(tier, Tier::new).getSeqNum());
或者：
String birthDay = StringUtils.defaultIfEmpty(contact.getCustomBirthdayDay(), "1");
或者：

1. 判断为null给默认值：

String pointValue = posReqVO.getAccount1000Value() == null? "0":posReqVO.getAccount1000Value();
String pointValue = Optional.ofNullable(posReqVO.getAccount1000Value()).orElse("0");

第六：这是一种常见的 JSON 解析操作，它会尝试获取指定字段的值，如果该字段不存在或为 null，则返回空字符串 ""。

String segmentNo = json.optString("SegmentNo")
String partnerFlag = customerJson.opt("PartnerFlag");
JSONObject jsonObject = customer.optJSONObject("Segments");

第七：jdk9及其以上：ifPresentOrElse() 的新方法。没有用jdk9，但是jdk8这样也能实现：

Optional.ofNullable(memberSegment)
            .map(existingSegment -> {
                CustomerLoyMemberSegmentPO updateSegmentPO = initMemberSegmentPO(memberCard, partnerCardDefnPO)
                    .setEndDate(null).setLastUpdated(DateUtils.utcNow());
                memberSegmentRepository.updateSegmentByIdAndSegNum(updateSegmentPO);
                return existingSegment;
            })
            .orElseGet(() -> {
                memberSegmentRepository.insert(memberSegmentPO);
                return null;
            });

第八：优化 if else，不想用if else，也可以考虑用函数式断言Predicate或BiPredicate 校验。

1：用三元运算和 Consumer 改造：

Consumer<List<CustomerLoyOrderTxnPO>> insertOperation = posConfirmPointVO.getIsRepeatedOrderFlag() ?
                        orderTxnRepository::signleInsertLoyCustomerTxnOrder :
                        orderTxnRepository::batchInsertLoyCustomerTxnOrder;
                insertOperation.accept(orderTxnsList);

2：使用三元运算符，最简单实现。

3：用Predicate检验改造：
        // 判断是否重复订单的条件
        Predicate<PosConfirmPointVO> isRepeatedOrder = PosConfirmPointVO::getIsRepeatedOrderFlag;
        // 定义处理重复订单的逻辑
        Runnable handleRepeatedOrder = () -> checkInsertCustomerBueventTxn(bueventTxnPO, account, buEventAccountDefnXmPOS);

        // 定义处理非重复订单的逻辑
        Runnable handleNonRepeatedOrder = () -> {
            customerBueventTxnRepository.insertCustomerBueventTxn(bueventTxnPO);
            upsertBueventAccountByType(memberId, eventId, account, buEventAccountDefnXmPOS);
        };
        // 根据订单是否重复执行不同的逻辑
        if (isRepeatedOrder.test(posConfirmPointVO)) {
            handleRepeatedOrder.run();
        } else {
            handleNonRepeatedOrder.run();
        }

第九：用jdk8 优化旧代码：

1. 旧代码：
    String authToken = getAuthToken();
    updateApolloConfig(count, authToken, apolloServiceConfig.parseItemUrl());

    if (isUpdateBlue) {
        updateApolloConfig(count, authToken, apolloServiceConfig.parseBlueItemUrl());
    }
 这样不更好:    
    Stream.of(apolloServiceConfig.parseItemUrl(),
                isUpdateBlue ? apolloServiceConfig.parseBlueItemUrl() : Stream.empty())
        .forEach(url -> updateApolloConfig(count, getAuthToken(), url)); 
        
2. 旧代码：
    List<Account> accounts = posConfirmReqVO.getAccounts();
    if (accounts.isEmpty()) {
        return;
    }
    accounts.stream()
        .filter(acc -> "1000".equals(acc.getId()))
        .findFirst()
        .ifPresent(x -> posConfirmReqVO.setAccount1000Value(x.getEarnValue()));
        
 这样更好:    
     Optional.ofNullable(posConfirmReqVO.getAccounts())
            .filter(accounts -> !accounts.isEmpty())
            .flatMap(accounts -> accounts.stream()
                .filter(acc -> "1000".equals(acc.getId()))
                .findFirst())
            .ifPresent(x -> posConfirmReqVO.setAccount1000Value(x.getEarnValue()));