@FunctionalInterface interface StringConsumer extends Consumer<String> { @Override public default void accept(String s) { System.out.println(s.toUpperCase()); } void ...

When calling findBySubstring() from ArticleAutocompleteServiceImpl - default method of interface is executed instead of implementation. Is it because of generics? What did I do wrong? How to keep this ...

I'm getting the following error while implementing the java.util.Iterator interface in my class: java: MenuIterator is not abstract and does not override abstract method remove() in java.util.Iterator....

Question: Need to understand why in case of Program 1 getting this misleading error, but in Program 2 it gives correct error? Also why unlike toString(), equals(Object), and hashCode(), overriding ...

When instantiating a class that has code to explicitly call a default method for an interface that it implements, a java.lang.VerifyError is thrown. This happens on Kitkat (API 19), but Lollipop and ...

How can I write a junit test case for default methods of interface with zero lines of code as mentioned below : public interface A{ default void method1(){ } }

I am a beginner in Java. I have a question about the abstract method in Interface. Is the following sampleMethod() an abstract method? My understanding is that it is not an abstract method due to ...

I have 4 Classes that look like this: public interface Foo<T> { ... default boolean isEmpty() { return false; //dummy value real implementation is not relevant for the problem } } public ...

I don't understand why an IllegalAccessError exception is thrown from the example below. The method foo() in Parent cannot be inherited by Child, because it is private. But trying to call the default ...

I have stumbled upon a strange issue working with default methods. Consider this situation: interface A { int method(); } interface B { default int method() { return 1; } } class ...

What is the point of making Functor a super class of Applicative and Monad. Both Applicative and Monad immediately imply the only implementation of Functor that abides by the laws as far as I can tell....

I've generated rest api with openAPI generator maven plugin and I've overridden the default method from MyApiDelegate interface, but POST request on /endpoint provides 501 NOT IMPLEMENTED as if I hadn'...

You often hear that methods in an interface have no implementation. However, in Java 8 it became possible to implement the default methods. But I'm interested. Was and is it possible to implement ...

Is there a way to easily override toSet(Collection<T> self) method from DefaultGroovyMethods? Its implementation uses HashMap public static <T> Set<T> toSet(Collection<T> self) ...

interface WithDefinitionsInter { default void definedMeth() { System.out.println("inside interface"); } } class WithDefinitionsImpl implements WithDefinitionsInter { ...