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Interface can be defined inside another class?
yes ,interface can be defined inside another class
What do you mean by inheriting the interface?
In object oriented programming, a derived class inherits the protected and public members of its base class. Those members therefore define the interface that is inherited by the derived class. The derived class may augment that interface to provide a more specialised implementation of the interface, without the need to re-write the generic interface of the base class. The implication is that the derived class is a more specialised form of the base class.
How do you write a Java class that implements the collection interface found in the java.util package?
Type in "implements java.util.Collection" after the class name.
Why protected access specifier is not in interfaces?
Because an interface is like a contract/skeleton which decides what the implementing class has to do. So, if any entity in an interface is protected, they would not be available to the class that is implementing the interface. Hence, all the variables and methods declared inside an interface are public by default
How do you create an interface?
by declaring in the header of the class: public/private interface [interfaceName] and do not write any method body(i.e. public void dance();)
Is Iterator a class or Interface?
Its an interface.
Difference between class and interface in java?
A class is a data type. An interface consists of the private, protected and public members of a class, allowing consumers of the class to interact with the class representation in a controlled manner. The private interface is only accessible to the class itself and to friends of the class. The protected interface is similar to the private interface but is also accessible to derivatives of the class. The public interface is fully accessible. The private and protected interfaces are intended purely for use by the class implementers while the public interface is intended for use by both consumers and implementers.
Is interface class a valid term?
Yes. An interface in essence is a java class and so you can use the term interface class. But, using the term class along with the term interface can cause ambiguity or misunderstandings among novice java developers. So, using the term "Interface" along would suffice to refer to a type of class which is the "Interface"
Why instance in abstract or interface?
we can make object of interface but in abstract we can not make object of it interface ab= new Classs(): in interface we maintain multiple inhetence by use of obj of interface we if inherit two class have same fun then we give the name of that interface and call the pertucular that fun interface ab= new class() ab.add(); but in Astract Class we cannot make object of it only class class wich inherit it can make object class ab2= new Class(); and by obj we call function of drived class ob2.add();
What is similarities between Abstract Class and Interface?
If a class has one abstract method ,the class has to be an abstract class.Methods can be implemented in abstract class.Whereas a interface is like a abstract class...the only difference being that the methods are never implemented in Interface.
Why use interfaces in Java?
an Interface is nothing but a contract as to how a class should behave. It just declares the behavior as empty methods and the implementing class actually writes the code that will determine the behavior. When you implement an interface, you're agreeing to adhere to the contract defined in the interface. That means you're agreeing to provide legal implementations for every method defined in the interface, and that anyone who knows what the interface methods look like can rest assured that they can invoke those methods on an instance of your implementing class. (Thy need not bother much about how you have implemented it. All they bother about is whether a method of the name mentioned in the interface is available or not) Now, you might stop me and ask, what if I implement an interface and opt not to write code for a method that I am supposed to? The answer is simple. The compiler wouldn't let you do that. You cannot successfully implement an interface without providing method implementation for all the methods declared inside the interface. This is how the java system ensures that when someone knows a certain method name in an interface and has an instance of a class that implements it, can actually call that method without fear that the method isnt implemented inside the class. Assuming an interface, Convertible, with two methods: openHood(), and setOpenHoodFactor(), the following class will compile: public class Ball implements Convertible { // Keyword 'implements' public void openHood() { } public void setOpenHoodFactor(int bf) { } } Ok, I know what you are thinking now. "This has got to be the worst implementation class that you have seen". Though it compiles and runs as well, it is actually doing nothing… the interface contract guarantees that the class implementing it will have a method of a particular name but it never guaranteed a good implementation. In other words, the compiler does not bother whether you have code inside your method or not. All it cares is if you have methods of the matching names as in the interface. That's all… Implementation classes must adhere to the same rules for method implementation as a class extending an abstract class. In order to be a legal implementation class, a nonabstract implementation class must do the following: • Provide concrete (nonabstract) implementations for all methods from the declared interface. • Follow all the rules for legal overrides. • Declare no checked exceptions on implementation methods other than those declared by the interface method, or subclasses of those declared by the interface method. • Maintain the signature of the interface method, and maintain the same return type (or a subtype). • It does not have to declare the exceptions declared in the interface method declaration
What is an interface and how will you go about implementing an interface?
an Interface is nothing but a contract as to how a class should behave. It just declares the behavior as empty methods and the implementing class actually writes the code that will determine the behavior. When you implement an interface, you're agreeing to adhere to the contract defined in the interface. That means you're agreeing to provide legal implementations for every method defined in the interface, and that anyone who knows what the interface methods look like can rest assured that they can invoke those methods on an instance of your implementing class. (Thy need not bother much about how you have implemented it. All they bother about is whether a method of the name mentioned in the interface is available or not) Now, you might stop me and ask, what if I implement an interface and opt not to write code for a method that I am supposed to? The answer is simple. The compiler wouldn't let you do that. You cannot successfully implement an interface without providing method implementation for all the methods declared inside the interface. This is how the java system ensures that when someone knows a certain method name in an interface and has an instance of a class that implements it, can actually call that method without fear that the method isn't implemented inside the class. Assuming an interface, Convertible, with two methods: openHood(), and setOpenHoodFactor(), the following class will compile: public class Ball implements Convertible { // Keyword 'implements' public void openHood() { } public void setOpenHoodFactor(int bf) { } } Ok, I know what you are thinking now. "This has got to be the worst implementation class that you have seen". Though it compiles and runs as well, it is actually doing nothing… the interface contract guarantees that the class implementing it will have a method of a particular name but it never guaranteed a good implementation. In other words, the compiler does not bother whether you have code inside your method or not. All it cares is if you have methods of the matching names as in the interface. That's all… Implementation classes must adhere to the same rules for method implementation as a class extending an abstract class. In order to be a legal implementation class, a nonabstract implementation class must do the following: • Provide concrete (nonabstract) implementations for all methods from the declared interface. • Follow all the rules for legal overrides. • Declare no checked exceptions on implementation methods other than those declared by the interface method, or subclasses of those declared by the interface method. • Maintain the signature of the interface method, and maintain the same return type (or a subtype). • It does not have to declare the exceptions declared in the interface method declaration.
