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When an interface method is implemented in a class it must be declared as?
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∙ 11y ago
Abstract type
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∙ 11y ago
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Can abstract method be overriden?
An overridden method is one which has already been implemented in the parent class with the same signature but has again been coded in the current class for functionality requirements. An abstract method is one which has only been declared in a class and would have to be implemented by the class that extends this abstract class. The implementation for the method is not available in the class in which it is declared.
What happens if a class doesn't implement all the methods defined in the interface?
It depends on how the class is declared.If the class is a normal class - Then the compiler will complain. All the methods in an interface must be implemented by the class to successfully compile the classIf the class is declared as abstract - Then the compiler will ignore the fact that a few methods are not implemented
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.
How do you use an interface?
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
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
Interface method have by default method public?
Yes, Interface mehtods are public by default so that they could be implemented by every class implementing the interfaces.
Can abstract method be overriden?
An overridden method is one which has already been implemented in the parent class with the same signature but has again been coded in the current class for functionality requirements. An abstract method is one which has only been declared in a class and would have to be implemented by the class that extends this abstract class. The implementation for the method is not available in the class in which it is declared.
What happens if a class doesn't implement all the methods defined in the interface?
It depends on how the class is declared.If the class is a normal class - Then the compiler will complain. All the methods in an interface must be implemented by the class to successfully compile the classIf the class is declared as abstract - Then the compiler will ignore the fact that a few methods are not implemented
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.
How do you use an interface?
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
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.
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 a predefined interface in java?
An interface is a collection of methods that must be implemented by the implementing class.An interface defines a contract regarding what a class must do, without saying anything about how the class will do it.Interface can contain declaration of methods and variables.implementing class must define all the methods declared in the interfaceIf a class implements an interface and does not implement all the methods then class itself must be declared as abstractVariables in interface automatically become static and final variableof the implementing classMembers of interface are implicitly public, so need not be declared as public.An interface must be implemented in class.
What is the difference of interface and class?
A (concrete) class defines all his methods and can have any kind of instance variable and is declared with the 'class' keyword. Unlike an interface that doesn't implements any of his methods and his variables must be static and final. An interface is defined with the 'interface' keyword.//This is a classpublic class MyClass{public String name;private int age;public void myMethod(){//do something}}//This is a interfaceinterface MyInterface {public static final String name;public static final int age;public void myMethod(); // This method is not implemented}An other difference is that a class can be inheritance by other class but a interface must be implemented using the keyword 'implements'.interface Runnable(){void run();}public class MyOtherClass implements Runnable{public void run(){// insert interesting code here}}
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.
Difference between interface and abstract class on uml?
In general, the differences are that interface has(1) no fields and(2) no implementation of methodsbut in UML interface may have features (fields), so the difference left is that interface in UML has no implemented methods while abstract class by definition is partially implemented class.
Why don't use abstract keyword when we declare a method in interface?
The abstract keyword signifies that the particular method will have no features in the class where it is declared and it is upto the child class to provide the functionality. In case of an interface, the method is already abstract by default and has no code inside it. So there is no actual point in using the abstract keyword there.
