英文:

How to check for any null field of Object in List<Object>?

问题

我有一个对象列表传递给方法如下。

```java
Student s = new Student (name,age,branch, year); // 学生原型

public void log(List<Student> items) { }

在方法内部，我需要检查每个学生对象中是否有任何null值，并记录该特定属性的空值以及相应的学生对象。是否有其他方法来检查这个，而不是使用以下方式：

items.stream().anyMatch(item -> item.getAge() == null ? System.out.println());

在实际情况中，我的对象包含超过30个属性，如果其中任何属性为null，我想要记录该null属性及其对应的对象。

<details>
<summary>英文:</summary>

I have a list of Object passed to a method as below.

```java
Student s = new Student (name,age,branch, year); // student prototype

public void log(List&lt;Student&gt; items) { }

Inside the method, I need to check for any null values in each student object and log that particular attribute which was null and the corresponding student object. Is there a way to check this other than using?:

items.stream().anyMatch(item -> item.getAge() == null ? System.out.println());

In actual scenario, my object contains more than 30 attributes and if any of the attribute is null, I want to log that null attributes and its corresponding object.

答案1

得分: 3

你需要逐个检查每个字段，如果想逐一检查它们并记录它们是否为空。

如果要迭代所有字段，你可以使用反射，但我会质疑这种用例的适用性。

请注意，像 int age 这样的原始数据类型不能为 null，所以你不需要检查它。另外，你对 anyMatch 的使用是不正确的，因为 System.out.println 不返回布尔值。

英文:

You're going to have to check each field individually if you want to check them one-by-one and log if they are null.

You could use reflection to iterate over all fields, but I would question the applicability of such a use-case.

Note that primtives like int age cannot be null, so you wouldn't need to check for it. Plus, your usage of anyMatch is incorrect as System.out.println does not return a boolean