Why Did Java and C# Choose to Avoid Multiple Inheritance?

Why Multiple Inheritance is Not Allowed in Java and C#

It is well-known that multiple inheritance, the ability for a class to inherit from multiple parent classes, is not permitted in Java or C#. While many resources simply state this fact, they often fail to delve into the underlying reasons behind this design decision.

Short Answer:

The reason is simply because the language designers decided not to include it.

Longer Explanation:

The designers of both .NET and Java reasoned that multiple inheritance added significant complexity to their languages while offering minimal benefits. The complexities involve:

• Conflict Resolution: Multiple inheritance introduces the issue of how to resolve conflicts when inheriting methods or properties with the same name from different parent classes.
• Redundancy Handling: In some scenarios, multiple inheritance can lead to duplicate inherited members. This can cause ambiguity and confusion.
• Implementation Overheads: Adding multiple inheritance introduces complexity in areas such as casting, layout, dispatch, field access, serialization, and generics.

Interviews with Language Designers:

Chris Brumme, who worked on the CLR for .NET, explained the decision further:

• Different languages have varying expectations for MI, making it challenging to implement a universal solution.
• True applications of MI are often limited, and alternatives like multiple interface inheritance or encapsulation can often suffice.
• Implementing MI would require significant changes to the language's implementation, affecting various areas of functionality.

For Java, the rationale is similar:

• Simplicity, familiarity, and a desire to avoid unnecessary C complexities were guiding principles in Java's design.
• The designers believed that multiple inheritance would cause more headaches than it would solve, based on their experience with C .

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