AbstractMethodError

Why This Happens

AbstractMethodError occurs at runtime when a class that should implement an abstract method does not. This typically happens due to binary incompatibility: the interface or abstract class was updated to add a new method, but the implementing class was compiled against the old version.

The Problem

// Interface added a new method in v2.0
// Implementation was compiled against v1.0
public class MyPlugin implements Plugin {
    // Missing newMethod() added in v2.0
}

The Fix

// Recompile against the current interface version
public class MyPlugin implements Plugin {
    @Override
    public void existingMethod() { /* ... */ }

    @Override
    public void newMethod() { /* Implement the new method */ }
}

Step-by-Step Fix

1. 1

   Identify the missing method

   Read the error to find which abstract method is not implemented and which class should implement it.

2. 2

   Check for version mismatches

   Verify that the implementing class and the interface/abstract class are compiled against the same version.

3. 3

   Recompile or update dependency

   Recompile the implementing class against the current interface version, or update the dependency to a compatible version.