What would happen, if Multiple Inheritance is possible, in Java?

If Java allowed multiple inheritance with classes, it could lead to serious ambiguity and complexity—especially when two parent classes define methods or fields with the same signature. This is famously known as the Diamond Problem.

💎 The Diamond Problem: A Classic Example

Imagine this structure:

   A
  / \
 B   C
  \ /
   D

• Class A has a method display().
• Both B and C inherit from A and override display().
• Now class D inherits from both B and C.

If D calls display(), which version should it inherit—B‘s or C‘s? This ambiguity is what Java avoids by not allowing multiple inheritance with classes.

🔥 What Would Go Wrong?

If Java allowed it:

• Compiler Confusion: It wouldn’t know which method to invoke.
• Memory Layout Issues: Object structure in memory would become unpredictable.
• Constructor Chaining Chaos: Which parent constructor should be called first?
• Maintenance Nightmare: Code would be harder to read, debug, and extend.

✅ Java’s Solution: Interfaces

Java sidesteps this by:

• Allowing multiple inheritance through interfaces.
• Since interfaces don’t hold state (only method signatures), there’s no ambiguity.
• From Java 8 onward, interfaces can have default methods, and if two interfaces have the same default method, the implementing class must explicitly override it to resolve the conflict.

🧠 Summary

If Java allowed multiple inheritance with classes, it would introduce ambiguity, complexity, and potential bugs. By restricting it and embracing interfaces, Java keeps its object model clean, predictable, and easier to manage.