Optional<?> kafkaMessage = Optional.ofNullable(record.value());
时间: 2023-10-28 21:51:34 浏览: 43
This line of code creates an Optional object called "kafkaMessage" that may or may not contain a non-null value. The value of this Optional object is set to the result of calling the "ofNullable" method on the "record.value()" object.
The "ofNullable" method is a static method of the Optional class that takes a nullable value as its parameter and returns an Optional object that contains the value if it is non-null, or an empty Optional if the value is null.
By using the Optional class, this code ensures that any subsequent operations on the "kafkaMessage" object will not result in a NullPointerException if the underlying value is null.
相关问题
Optional<String> optional = Optional.ofNullable(userId);
Optional<String> optional = Optional.ofNullable(userId);这段代码的意思是创建了一个可以包含null值的Optional对象。如果userId不为null,则Optional对象的值为userId;如果userId为null,则Optional对象为空。可以通过调用isPresent()方法来判断Optional对象是否为空。<span class="em">1</span><span class="em">2</span><span class="em">3</span>
#### 引用[.reference_title]
- *1* *2* *3* [Optional用法](https://blog.csdn.net/Carrots_vegetables/article/details/109289415)[target="_blank" data-report-click={"spm":"1018.2226.3001.9630","extra":{"utm_source":"vip_chatgpt_common_search_pc_result","utm_medium":"distribute.pc_search_result.none-task-cask-2~all~insert_cask~default-1-null.142^v93^chatsearchT3_1"}}] [.reference_item style="max-width: 100%"]
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private List<Integer> getSingleList(Class<?> clz, String method) { Optional<Object> optional = ClzUtils.callSingletonMethod(clz, method, SP_REGISTRY.get(clz)); return optional.flatMap(obj -> obj instanceof List ? Optional.of((List<Integer>) obj) : Optional.empty()) .orElse(new ArrayList<>()); } 怎么样不会告警
这段代码中的告警可能是因为类型转换不安全,建议进行以下修改:
1. 对于 `ClzUtils.callSingletonMethod` 方法的调用,可以使用泛型来限定返回值的类型,并使用 `Optional` 类型来避免空指针异常,例如:
```
Optional<List<Integer>> optional = ClzUtils.<List<Integer>>callSingletonMethod(clz, method, SP_REGISTRY.get(clz));
```
2. 在对 `optional` 进行操作之前,可以先进行空判断,例如:
```
if (optional.isPresent()) {
List<Integer> list = optional.get();
// ...
}
```
3. 如果你确定 `SP_REGISTRY.get(clz)` 返回的对象一定是指定类的单例对象,可以使用 `@SuppressWarnings("unchecked")` 注解来消除告警,例如:
```
@SuppressWarnings("unchecked")
List<Integer> list = (List<Integer>) ClzUtils.callSingletonMethod(clz, method, SP_REGISTRY.get(clz)).orElse(new ArrayList<>());
```
需要注意的是,使用 `@SuppressWarnings` 注解时,要确保代码的类型安全,否则可能会发生运行时异常。