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What is difference between abstract class and interface in core java give brief answer with example?
Differences:Abstract class can also contain method definitions but an interface can contain only declarationsAll variables in an interface are by default public static and final whereas in Abstract class it is notAn interface can be considered as a pure abstract class that contains no method implementations and contains only declarations.
Can you have a final abstract class?
No. The abstract keyword means that you cannot instantiate the class unless you extend it with a subclass. The final keyword means that you cannot create subclasses of that class.Combining them would lead to an unusable class, so the compiler will not let this happen.
What is the difference between an interface and an abstract class?
We can't instantiate both interfaces and abstract classes.The only one difference between them is that an interface can't contain concrete(fully defined) methods where as an abstract class may contain them.An abstract class not necessarily contain abstract methods. we can make a class as abstract class even it does not has any abstract methods.When there is a need to write both abstract and concrete methods in a single unit we have to use an abstract class instead of an interface since an interface cant contain concrete methods.All the fields(or properties) of an interface are by default 'static final' even when you don't mention explicitly. And all methods are 'public abstract'.But in an abstract class we can have any type of fields and methods.
When do you declare method or class final?
final is a keyword.it can be used for three posibilities. they are ->we can assign the variable as final. to declaring the variable as final to avoid the reusability of a variable. now i display small program for this type. class A { final int i=10; a(int b) { i=b; System.out.println(i); } } public static void main(String args[]) { A x=new A(20); } } to execute this program .we have an error message.i.e.,the variable i can not be override. ->to use method have final keyword it can not be override.and also ->to use classes has final they can not be inhereted to sub classes.
A final class can have instances?
Yes. You cannot inherit a final class but very well instantiate a final class
What is the difference between abstract class and final class?
20
Can you define a class as final and abstract both?
Yes, a class can be defined as final and abstract also.
What is difference between abstract class and interface in core java give brief answer with example?
Differences:Abstract class can also contain method definitions but an interface can contain only declarationsAll variables in an interface are by default public static and final whereas in Abstract class it is notAn interface can be considered as a pure abstract class that contains no method implementations and contains only declarations.
Can you have a final abstract class?
No. The abstract keyword means that you cannot instantiate the class unless you extend it with a subclass. The final keyword means that you cannot create subclasses of that class.Combining them would lead to an unusable class, so the compiler will not let this happen.
What is the difference between an interface and an abstract class?
We can't instantiate both interfaces and abstract classes.The only one difference between them is that an interface can't contain concrete(fully defined) methods where as an abstract class may contain them.An abstract class not necessarily contain abstract methods. we can make a class as abstract class even it does not has any abstract methods.When there is a need to write both abstract and concrete methods in a single unit we have to use an abstract class instead of an interface since an interface cant contain concrete methods.All the fields(or properties) of an interface are by default 'static final' even when you don't mention explicitly. And all methods are 'public abstract'.But in an abstract class we can have any type of fields and methods.
When do you declare method or class final?
final is a keyword.it can be used for three posibilities. they are ->we can assign the variable as final. to declaring the variable as final to avoid the reusability of a variable. now i display small program for this type. class A { final int i=10; a(int b) { i=b; System.out.println(i); } } public static void main(String args[]) { A x=new A(20); } } to execute this program .we have an error message.i.e.,the variable i can not be override. ->to use method have final keyword it can not be override.and also ->to use classes has final they can not be inhereted to sub classes.
A final class can have instances?
Yes. You cannot inherit a final class but very well instantiate a final class
Write EBNF descriptions for A java class definition header statement?
® {} class [extends class_name] [implements {, }] ® public | abstract | final ® {} class [extends class_name] [implements {, }] ® public | abstract | final
What are the differences between an abstract class and an interface in java?
They are very different. An abstract class is a class that represents an abstract concept (google define "abstract" if you're unsure) such as 'Thoughts' or 'BankAccount'. When a class is defined as abstract it cannot be used (directly) to create an object. Abstract classes are used as super-classes so that all of their subclasses inherit all methods. Interfaces can be thought of as contracts with all of their implementing classes. They simply require all implementing classes to have methods with the same signature as that defined in the interface, but such methods can behave as appropriate. Hope that helps :)
What is the difference between an abstract and a conclusion?
An abstract is a brief summary of a research paper, usually including the objectives, methods, results, and conclusions of the study. It is located at the beginning of the paper to provide readers with an overview of the study. On the other hand, a conclusion is the final section of a research paper where the main findings and their implications are discussed, summarizing the key points of the study.
What can be declared in an abstract class?
Abstract classes are to be extended until to a concrete class.Can have both abstract & non abstract methods.An Abstract class can not be instantiated.A non abstract class can be extended to an abstract class.If At least one abstract method present in a class then that class must be abstract.abstract & final modifiers can never be together.abstract classes can have both abstract methods & non abstract methods.
Abstract class vs interface?
Comparison between an Abstract Class and an Interface:While an abstract class can define both abstract and non-abstract methods, an interface can have only abstract methods. Another way interfaces differ from abstract classes is that interfaces have very little flexibility in how the methods and variables defined in the interface are declared. These rules are strict:
