What implements the Comparable interface?

What implements the Comparable interface?

Since the Member class implements the Comparable interface, it is possible to sort the list by using the sorted method. In fact, objects of any class that implement the Comparable interface can be sorted using the sorted method.

What method must a class contain to implement the comparable interface?

For any class to support natural ordering, it should implement the Comparable interface and override it’s compareTo() method. It must return a negative integer, zero, or a positive integer as this object is less than, equal to, or greater than the specified object. Note that method must throw an exception if y.

Which method do we need to implement in the Java Lang comparable interface?

We can implement the Comparable interface with the Movie class, and we override the method compareTo() of Comparable interface.

What are the benefits of implementing the Comparable interface?

The benefit of implementing the interface is that some methods specifically require object that implements the Comparable interface. It gives them a guarantee that the object you’re passing has a compareTo method with the correct signature.

Why would you implement a comparable interface for your class what’s it’s used for?

Comparable interface is mainly used to sort the arrays (or lists) of custom objects. Before we see how to sort an objects of custom objects, lets see how we can sort elements of arrays and Wrapper classes that already implements Comparable.

Can an interface inherit more than one interface in Java?

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.

Can an interface inherit a class?

An interface can inherit multiple interfaces but cannot inherit a class. An abstract class can inherit a class and multiple interfaces. An interface cannot declare constructors or destructors.

Can an interface have a constructor?

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.

Can an interface implement a class?

Like abstract classes, interfaces cannot be used to create objects (in the example above, it is not possible to create an “Animal” object in the MyMainClass) Interface methods do not have a body – the body is provided by the “implement” class. On implementation of an interface, you must override all of its methods.

What is the purpose of interfaces?

Purpose of the interface Provides communication − One of the uses of the interface is to provide communication. Through interface you can specify how you want the methods and fields of a particular type.

How do you implement two interfaces?

A Java class can only extend one parent class. Multiple inheritance ( extends ) is not allowed. Interfaces are not classes, however, and a class can implement more than one interface. The parent interfaces are declared in a comma-separated list, after the implements keyword.

How do you implement only one interface?

But of course, you can override them into sub-classes, if you need that. The answer is simple: don’t implement the interface. If you do implement it, either your class must be abstract, or you must implement all the methods defined in the interface (unless you are already inheriting an implementation).

Can you override interface methods?

You can make the methods default in the interface itself, Default methods are introduced in interfaces since Java8 and if you have default methods in an interface it is not mandatory to override them in the implementing class.

Can we override interface method?

If a base class already implements an interface and a derived class needs to implement the same interface but needs to override certain methods, you must reimplement the interface and set only the interface methods which need overriding. Both implement the ViewerEditable interface. …

Do we need to implement all methods of interface?

Yes, it is mandatory to implement all the methods in a class that implements an interface until and unless that class is declared as an abstract class. Declare the class as an abstract class, as a result, forces you to subclass the class (and implement the missing methods) before you can create any objects.

What happens if a class does not implement all members of an interface?

If you don’t implement all methods of your interface, than you destroy the entire purpose of an interface. We can override all the interface methods in abstract parent class and in child class override those methods only which is required by that particular child class.

Is it necessary to implement all methods of abstract class?

Yes you must implement all the methods present in an abstract class. As the purpose of abstract class is purely to create a template for the functions whose implementation is decided by the class implementing them. So if you don’t implement them, then you are breaking the concept of abstract class.

How many interfaces can a class implement?

Your class can implement more than one interface, so the implements keyword is followed by a comma-separated list of the interfaces implemented by the class.

What happens if a class implement 2 interfaces having same methods?

A class implementation of a method takes precedence over a default method. So, if the class already has the same method as an Interface, then the default method from the implemented Interface does not take effect. However, if two interfaces implement the same default method, then there is a conflict.

How do you declare an interface class?

An interface is declared by using the interface keyword. It provides total abstraction; means all the methods in an interface are declared with the empty body, and all the fields are public, static and final by default. A class that implements an interface must implement all the methods declared in the interface.

What is difference between class and interface?

A class describes the attributes and behaviors of an object. An interface contains behaviors that a class implements. A class may contain abstract methods, concrete methods. An interface contains only abstract methods.

What does an interface contain?

Interfaces in Java In the Java programming language, an interface is a reference type, similar to a class, that can contain only constants, method signatures, default methods, static methods, and nested types. Method bodies exist only for default methods and static methods.

Can an abstract class implement an interface?

Java Abstract class can implement interfaces without even providing the implementation of interface methods. Java Abstract class is used to provide common method implementation to all the subclasses or to provide default implementation.

Why interface is used instead of abstract class?

The short answer: An abstract class allows you to create functionality that subclasses can implement or override. An interface only allows you to define functionality, not implement it. And whereas a class can extend only one abstract class, it can take advantage of multiple interfaces.

What is the difference between abstraction and interface?

Abstract class and interface both are used to achieve abstraction where we can declare the abstract methods. Abstract class and interface both can’t be instantiated….Difference between abstract class and interface.

Abstract class	Interface
7) An abstract class can be extended using keyword “extends”.	An interface can be implemented using keyword “implements”.

Can an abstract class have a constructor?

In abstract class, we have an instance variable, abstract methods, and non-abstract methods. We need to initialize the non-abstract methods and instance variables, therefore abstract classes have a constructor. This is also one of the reasons abstract class can have a constructor.

Can abstract class have body?

Abstract methods cannot have body. Abstract class can have static fields and static method, like other classes. An abstract class cannot be declared as final. Only abstract class can have abstract methods.

Can an abstract class have a main method?

Yes, you can use the main method in abstract class. The abstract is applicable to the object so there is no problem if it contains the main method. In main method, you can not create an instance of the abstract class but you can instantiate other concrete class.

Can we make abstract class as final?

No, you cannot make an abstract class or method final in Java because the abstract and final are the mutually exclusive concept. An abstract method must be overridden to be useful and called but when you make the abstract method final it cannot be overridden in Java, hence there would be no way to use that method.