MyBatis Error: Unable to Instantiate Interface (NoSuchMethodException)

This error message indicates that MyBatis is unable to instantiate the com.scq.demo6.mapper.ClassroomMapper interface. This is often caused by the lack of a default (no-argument) constructor within the interface.

To resolve this, you need to add a default constructor to your com.scq.demo6.mapper.ClassroomMapper interface. Here's how:

public interface ClassroomMapper { 
    // ... other methods ... 

    // Add the default constructor 
    public ClassroomMapper() { 
    } 
} 

After adding the default constructor, recompile your project and rerun your code. This should resolve the NoSuchMethodException and allow MyBatis to successfully instantiate your ClassroomMapper interface.

Explanation:

MyBatis relies on reflection to create instances of your mapper interfaces. When MyBatis tries to instantiate an interface, it looks for a constructor that matches the given arguments. In this case, since there are no arguments provided, MyBatis expects a default constructor (a constructor that takes no arguments). Without this constructor, MyBatis is unable to create an instance of the interface, leading to the NoSuchMethodException error.