While it's true that a class can directly inherit from at most one other class (from exactly one other class except for java.lang.Object, which inherits from exactly zero other classes), a class or an interface can inherit from multiple interfaces. E.g. "class SoAndSo extends X implements A, B, C", or "interface HowsThat implements D, E, F".

There are special rules for handling conflicts due to multiple inheritance.
If interface A and interface B both have a constant with the same name, then class SoAndSo has to use a qualified name to refer to either of those constants, even though in the absence of conflict a simple name would suffice.
If interface A and interface B both define a method called "CallMeSometime" with the same signature but different return types, then no class is allowed to implement, directly or indirectly both A and B. See the Java Language Specification, Chapter 8.

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• Inheritance from interfaces can be multiple - Authored by: Ed L. on Saturday, May 05 2012 @ 12:06 PM EDT