Cannot invoke "com.example.demo1.entity.Users.getName()" because "users" is null
时间: 2023-12-25 17:14:06 浏览: 34
This error means that you are trying to call the `getName()` method on a null object reference. In other words, the `users` object has not been initialized properly, or it has been set to null somewhere in your code.
To fix this error, you need to make sure that the `users` object is properly initialized before calling any of its methods. This could involve checking for null values before calling methods, or initializing the object with default values if it is null.
It's also possible that the error is caused by a typo or other mistake in your code. Make sure that you are referencing the correct object, and that you are calling the correct method on that object.
相关问题
Cannot invoke String.equals(Object) because pro1 is null
这个错误是因为你在一个 null 变量上调用了 equals() 方法。你需要先检查变量是否为 null,然后再调用 equals() 方法。例如:
```
if (pro1 != null && pro1.equals("someValue")) {
// do something
}
```
这样就可以避免空指针异常。
java.lang.NullPointerException: Cannot invoke "com.example.mysqldemo.mapper.
java.lang.NullPointerException是Java中常见的运行时异常之一。它表示在尝试使用一个空对象的方法或属性时发生了错误。具体来说,"Cannot invoke"这个错误信息表明在调用一个方法时,对象为空,无法执行相应的操作。
在你提到的错误信息中,"com.example.mysqldemo.mapper"是一个包名,而后面的部分可能是该包下的某个类或方法。由于对象为空,所以无法调用该类或方法,导致出现了NullPointerException。
解决这个问题的方法通常是检查代码中是否存在空对象的情况,并在使用对象之前进行判空处理。可以使用条件语句或者使用Java 8引入的Optional类来避免空指针异常。