Can we use protected in interface?

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The protected members can typically be accessed within the same class or a class that inherits it. However, we will implement the interface; we do not inherit it. As a result, an interface’s members cannot be protected.

Can we use protected in interface in Java?

The protected modifier is not currently supported for interface methods in the Java language specification.

Can we use private and protected in interface?

No, Java does not support the definition of private and protected modifiers for interface members. We can say that because of this, members defined in interfaces are implicitly public or, to put it another way, are public by default.

Can we use protected in interface C#?

In C# 8, it is possible to have all explicit access modifiers, including public, private, protected, internal, and protected internal, for all interface member types, including methods, properties, and indexers.

CAN interface have protected access modifiers in Java?

Class and interfaces are exempt from the protected access modifier.

Can we have constructor in interface?

In Java, an interface cannot contain a constructor. As of Java 7, you can only have public, static, final variables and public, abstract methods.

Can you declare protected abstract method in interface?

An abstract method may indeed be declared protected. If you do this, you can use its subclasses or classes in the same package to access it.

Can we declare interface as final?

interface methods cannot be considered final. Cannot be deemed conclusive.

Can a static method be private?

In Java 9, it is possible to include private methods or private static methods in an interface.

Can we use virtual method in interface?

In C# 8, virtual interface members are possible. Unless the sealed or private modifier is applied, any interface member whose declaration contains a body is a virtual member. Therefore, unless the sealed or private modifier is used, every default interface method is virtual by default.

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Can we have data members in interface?

Interfaces CAN indeed include member variables. However, these variables must be implicitly final, public, and static (without any keyword definition). This means that one can only declare constants within interfaces. Interfaces cannot be used to declare instance variables.

Can we have default method in interface?

Interfaces may include default methods starting with Java 8 and later. Similar to static methods in classes, interfaces can also have static methods. Old interfaces can now have new methods without affecting existing code thanks to the introduction of default methods, which offer backward compatibility for them.

Which modifier Cannot be applied to an interface method?

Class and interfaces are exempt from the protected access modifier.

Can we instantiate abstract class?

We’ve all heard of abstract classes, which are classes that can have abstract methods but cannot be instantiated. Java does not allow us to instantiate abstract classes because they are incomplete and therefore unable to be used.

CAN interface have variables?

An interface, like a class, can have variables and methods, but by default, the methods declared in an interface are abstract (only method signature, no body).

Can we write non abstract method in interface?

Only abstract methods are allowed for interfaces. Both abstract and non-abstract methods can be found in an abstract class.

Can functional interface have 2 abstract methods?

An interface that only has one abstract method is said to be functional. They are only capable of displaying one functionality.

Can we declare constructor as static?

No, we cannot define a static constructor in Java. A compile-time error will occur if we attempt to define a static constructor in Java. Static typically refers to a class level. The instance variables’ initial values will be set using a constructor.

Can constructor be static?

Java constructors aren’t allowed to be static

The fact that a Java constructor cannot be static is one of its key characteristics. We are aware that the static keyword refers to a class rather than a class object. There is no use of the static constructor because a constructor is called whenever an object of a class is created.

Can we override static method in Java?

Static binding is used to bond static methods at compile time. Therefore, in Java, static methods cannot be overridden.

Can class extend interface?

Because extending from a class and implementing an interface are two distinct ideas, a class cannot extend an interface. As a result, they employ various keywords.

Can we overload private method in Java?

In Java, private methods can be overloaded, but you can still access them from the same class.

Can we have non public method in interface?

Since Java 9’s release, an interface can have private methods. Use of private methods is advised for sensitive code because they are only visible within the class or interface. The inclusion of private methods in interfaces was made for this reason.

Can abstract class have constructor?

Even though they are only called from their concrete subclasses, abstract classes in Java are still able to have constructors.

Can class implements interface?

You cannot directly instantiate an interface. Any class or struct that implements the interface implements its members. Multiple interfaces may be implemented by a class or struct. A class may implement one or more interfaces in addition to inheriting from a base class.

Can we declare a static function as virtual?

Because a virtual function is by definition a base class member function that depends on a particular object to determine which implementation of the function is called, it cannot be global or static.

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Can interface be internal?

A public interface has no private members. The interface is implemented by Class1. It can only be internal because it derives from an internal interface; private root types are not permitted. However, you didn’t designate the IntEnumType as public in your code, so it defaults to private.

Can interfaces be private?

A nested interface is the only type of interface that can be private. A top-level class or interface can either be package-private or public.

Can we create object of interface?

Interfaces cannot be used to create objects, just like abstract classes (in the example above, it is not possible to create an “Animal” object in the MyMainClass) Interface methods lack a body; instead, the “implement” class supplies one. You must override every one of an interface’s methods when implementing it.

Can we have multiple default methods in interface?

Numerous Defaults

It is possible for a class to implement two interfaces with the same default methods because interfaces have default functions. How to clear up this ambiguity is shown in the code below. The first course of action is to write your own method and replace the default implementation with it.

Why interface has default method?

You can extend the functionality of current interfaces using default methods, which also guarantee binary compatibility with code created for earlier iterations of those interfaces. In particular, default methods let you extend existing interfaces with new methods that take lambda expressions as parameters.

Can we have concrete methods in interface?

If you attempt to have a concrete method (the one with a body) in an interface, you will receive a compile-time error that reads, “Interface abstract methods cannot have body.”

Are all methods in an interface public?

The classes that implement the interface are responsible for defining the implementation. Even if the method declaration does not include the public keyword, all methods in an interface are public.

Can we extend multiple interfaces in Java?

Yes, we are capable of doing it. In Java, an interface can extend different interfaces.

Can a class be declared with a protected modifier?

The protected access modifier can be accessed both inside and outside of a package, but only via inheritance. The constructor, method, and data member are all compatible with the protected access modifier. It isn’t applicable in class.

Can a static class be extended?

A static nested class lacks access to the instance variables and methods of the outer class, just like static members do. With another inner class, you can extend a static inner class.

Can we declare abstract class without abstract method?

In Java, it is possible to declare an abstract class without any abstract methods. An abstract class means that the user sees the function definition but the implementation is hidden.

Can static class be instantiated?

A static class can’t be created from scratch. Without creating an instance of the class, all members of a static class can be accessed directly by using the class name. A static class, called CSharpCorner, is demonstrated in the code that follows.

What is Polymorphism in Java?

Polymorphism in Java refers to a class’s capacity to offer various implementations of a method depending on the kind of object it receives as a parameter. Simply put, polymorphism in Java enables us to carry out the same action in a variety of ways.

Are interfaces static?

Java interfaces cannot be instantiated on their own, so interface variables must be static. The variable must have its value assigned in a static context with no instances. The last modifier guarantees that the value assigned to the interface variable is an actual constant that cannot be changed.

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Can abstract method have a body?

There can be no body in abstract methods. Like other classes, abstract classes can have static fields and static methods. A final declaration cannot be made for an abstract class.

Can final method be overridden?

If a method cannot be overridden by subclasses, it is indicated by the final keyword in the method declaration.

Can abstract method be private?

A class method that is private prevents access from outside the current class, including from its child classes. However, if a method is abstract, you must override it in a subclass before using it from the same class. The abstract method cannot be private as a result.

Can abstract class be empty?

To group classes together, use an empty abstract class. This is done to demonstrate some intention and uphold the idea of a class having only one goal, or single responsibility. You use an interface in the example rather than a blank abstract class. For that, packages are used.

Can we create logic in abstract class?

For an abstract class, we cannot make any objects.

Is @FunctionalInterface mandatory?

The compiler does not throw an error if the functional interface is not annotated with the @FunctionalInterface tag. However, it is advisable to use the @FunctionalInterface annotation to prevent the unintentional addition of extra methods.

Is thread a functional interface?

Since this is a functional interface, a lambda expression or method reference can use it as the assignment target. Any class whose instances are meant to be executed by a thread should implement the Runnable interface. A method called run with no arguments must be defined for the class.

Why wrapper classes are immutable in Java?

Due to the immutability of all primitive wrapper classes in Java (Integer, Byte, Long, Float, Double, Character, Boolean, and Short), operations like addition and subtraction create new objects rather than altering the existing ones.

Can we break immutable class in Java?

A more thorough response: Serialization can indeed undermine immutability. It looks fantastic. It is threadsafe, elegant, small, and immutable (you cannot change start or end after initialization). Keep in mind that serialization is an additional method for creating objects (and it is not using constructors).

Can we overload the constructor?

Similar to function overloading, constructor overloading is a possibility. The class name is the same for overloaded constructors, but they take a different number of arguments. The appropriate constructor is called based on the quantity and kind of arguments passed.

Can a constructor be private?

Yes, we are allowed to make a constructor private. We are unable to create an object of a class if we declare a constructor as private. This private constructor can be utilized with the Singleton Design Pattern.

Can constructor return a value?

The constructor does not, in fact, return anything.

Why constructor is not overridden?

In Java, constructor overriding is not possible. This is due to the fact that Constructor has the appearance of a method but its name should be the class name and it has no return value. Overriding entails precisely stating in the Sub class what was previously declared in the Super class.

Can we make constructor static?

No, we cannot define a static constructor in Java. A compile-time error will occur if we attempt to define a static constructor in Java. Static typically refers to a class level. The instance variables’ initial values will be set using a constructor.

Can we overload abstract method in Java?

All abstract methods of an abstract class must be overridden by a subclass. It’s not necessary to override abstract methods if the subclass is declared abstract, though.