evaluated to a null value
时间: 2023-04-28 22:03:47 浏览: 75
evaluated to a null value的意思是“被评估为null值”。在计算机编程中,当一个表达式或变量被计算或赋值时,如果其结果为null,则会出现这种情况。这通常表示该值未被正确初始化或未被正确处理。需要进一步检查代码以确定问题的根本原因。
相关问题
he expression 'userList' evaluated to a null value.
It seems like you are encountering an error where the expression 'userList' is evaluated to a null value. This error typically occurs when you are trying to access or use a variable or object that has not been properly initialized or assigned a value.
To resolve this issue, you can check if the 'userList' variable has been initialized or assigned a value before using it. You can do this by using conditional statements or by adding null checks.
For example, you can use an if statement to check if 'userList' is null before using it:
```
if (userList != null) {
// Your code that uses 'userList' goes here
} else {
// Handle the case when 'userList' is null
}
```
Alternatively, you can use the null coalescing operator (??) to provide a default value if 'userList' is null:
```
var userList = getUserList() ?? new List<User>();
// Your code that uses 'userList' goes here
```
Remember to replace `getUserList()` with the actual code that retrieves or initializes the 'userList' variable in your specific scenario.
nested exception is org.apache.ibatis.builder.BuilderException: The expression 'ids' evaluated to a null value.
nested exception is org.apache.ibatis.builder.BuilderException: The expression 'ids' evaluated to a null value.这个错误通常是由于在Mybatis的配置文件中执行了一个空的表达式导致的。可以通过检查代码,确保在配置文件中正确设置了对应的参数值。一种可能的解决办法是在传递给Mybatis的查询语句中确保参数值不为空,或者在配置文件中添加一个判断条件来处理空值。 <span class="em">1</span><span class="em">2</span><span class="em">3</span>
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