In Java, interfaces can contain both default and static methods, introduced in Java 8. Default methods allow you to add new methods to an interface without breaking existing implementations. They provide a way to define a method with a body, which can be overridden by implementing classes if needed. The syntax for a default method is public default void methodName() { /* method body */ }. This feature enhances backward compatibility, as existing classes that implement the interface do not need to implement the new method unless they choose to override it ³⁵.

Static methods in interfaces, on the other hand, are utility methods that belong to the interface itself rather than to instances of classes implementing the interface. They cannot be overridden by implementing classes and are called using the interface name, like InterfaceName.methodName(). The syntax for a static method is public static void methodName() { /* method body */ } ³⁴.

Both default and static methods can coexist in an interface, providing flexibility in design and implementation ¹².