Can we inherit functional interface in Java?

You can't inherit any functional interface to another functional interface. Because it breaks the law of functional interface has exactly one abstract method.
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Can a functional interface extend inherit another interface?

A functional interface can extends another interface only when it does not have any abstract method.
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Can we inherit interface?

Interfaces can inherit from one or more interfaces. The derived interface inherits the members from its base interfaces. A class that implements a derived interface must implement all members in the derived interface, including all members of the derived interface's base interfaces.
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Can interface inherit another interface java?

An interface cannot implement another interface in Java. An interface in Java is essentially a special kind of class. Like classes, the interface contains methods and variables. Unlike classes, interfaces are always completely abstract.
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Can we have 2 abstract method in functional interface?

A functional interface is an interface that contains only one abstract method. They can have only one functionality to exhibit.
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#7.5 Java Tutorial | Functional Interface | Lambda Expression



Can functional interface have static methods?

A functional interface can contain default and static methods which do have an implementation, in addition to the single unimplemented method. The above interface still counts as a functional interface in Java, since it only contains a single non-implemented method.
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Can functional interface have zero abstract methods?

A Functional Interface has one abstract method and several default or static methods are possible.
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Can we inherit abstract class?

An abstract class cannot be inherited by structures. It can contains constructors or destructors. It can implement functions with non-Abstract methods.
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Can you inherit multiple interfaces?

No you cannot inherit multiple interfaces, because interfaces cannot be inherited. Interfaces are IMPLEMENTED, not inherited.
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Can an interface inherit object class?

Object class. Interfaces in java don't inherit from Object class. They don't have default parent like classes in java.
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Can a class inherit multiple interfaces in Java?

The Java programming language supports multiple inheritance of type, which is the ability of a class to implement more than one interface. An object can have multiple types: the type of its own class and the types of all the interfaces that the class implements.
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Can interface be a parent class?

A Java class can only extend one parent class. Multiple inheritance is not allowed. Interfaces are not classes, however, and an interface can extend more than one parent interface. The extends keyword is used once, and the parent interfaces are declared in a comma-separated list.
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Can we have constructor in interface?

No, you cannot have a constructor within an interface in Java. You can have only public, static, final variables and, public, abstract, methods as of Java7. From Java8 onwards interfaces allow default methods and static methods. From Java9 onwards interfaces allow private and private static methods.
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Can we override functional interface?

We can override the default method as it is available to the class that implements the interface. In the same way, we can invoke it using the implementation class object from the interface directly without overriding it.
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Can we override object class methods in functional interface?

An interface cannot declare any of the methods of the object class as a default method. This restriction may be surprising, especially since the interface does not inherit from object. Behind the scenes, an interface implicitly declares a public abstract method for most of the object's method.
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Can we have default method in functional interface?

You can have default methods in a functional interface but its contract requires you to provide one single abstract method (or SAM). Since a default method have an implementation, it's not abstract. Conceptually, a functional interface has exactly one abstract method.
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Which inheritance is not supported in Java?

Multiple inheritance is not supported by Java using classes, handling the complexity that causes due to multiple inheritances is very complex.
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Can interface extends abstract class in Java?

Interface can't provide the implementation of an abstract class. Inheritance vs Abstraction: A Java interface can be implemented using the keyword “implements” and an abstract class can be extended using the keyword “extends”.
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Can we inherit private class?

Members of a class that are declared private are not inherited by subclasses of that class. Only members of a class that are declared protected or public are inherited by subclasses declared in a package other than the one in which the class is declared. The answer is No. They do not.
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Can static class be inherited?

Static classes are sealed and therefore cannot be inherited. They cannot inherit from any class except Object. Static classes cannot contain an instance constructor. However, they can contain a static constructor.
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Can we inherit constructor in Java?

Constructors are not members, so they are not inherited by subclasses, but the constructor of the superclass can be invoked from the subclass.
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Is callable functional interface?

Interface Callable<V>

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference. A task that returns a result and may throw an exception. Implementors define a single method with no arguments called call .
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Can we have multiple default methods in interface?

Multiple Defaults

With default functions in interfaces, there is a possibility that a class is implementing two interfaces with same default methods. The following code explains how this ambiguity can be resolved. First solution is to create an own method that overrides the default implementation.
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Is Comparator a functional interface?

Answer. Yes, Comparator is a functional interface. The equals is an abstract method overriding one of the public methods of java. lang.
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Is lambda only for functional interfaces?

No, all the lambda expressions in this code implement the BiFunction<Integer, Integer, Integer> function interface. The body of the lambda expressions is allowed to call methods of the MathOperation class. It doesn't have to refer only to methods of a functional interface.
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