what is the difference between the abstract class and interface?
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The key technical differences between an abstract class and an interface are: Abstract classes can have constants, members, method stubs (methods without a body) and defined methods, whereas interfaces can only have constants and methods stubs.
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In Java, an abstract class can implement an interface, and not provide implementations of all of the interface's methods. It is the responsibility of the first concrete class that has that abstract class as an ancestor to implement all of the methods in the interface.
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Abstract classes get instantiated indirectly via derived classes. They provide common behaviour and instance state, but signal that more is required and must be provided by derived concrete classes. ... Static classes cannot be instantiated, and any state is at the class level rather than the instance level.
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No, an interface is not a class in Java. An interface is a type and all reference types (i.e. non-primitive types) handle quite similarly in Java. Often when people say "class" they are actually referring to a "reference type".
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Virtual methods have an implementation and provide the derived classes with the option of overriding it. Abstract methods do not provide an implementation and force the derived classes to override the method. So, abstract methods have no actual code in them, and subclasses HAVE TO override the method.
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20 Answers. An object's class defines how the object is implemented . The class defines object's internal state and the implementation of its operations. In contrast, an object's type only refers to its interface - a set of requests to which it can respond.
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3) Abstraction lets you focus on what the object does instead of how it does, while Encapsulation means hiding the internal details of how an object works. ... 5) In Java, Abstraction is supported using interface and abstract class while Encapsulation is supported using access modifiers e.g. public, private and protected.
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Abstract methods can be either public, protected or default access (package visible). Unlike interfaces abstract classes can contain fields that are not static and final. *Abstract classes can have private methods, but not abstract private methods.
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Main difference is methods of a Java interface are implicitly abstract and cannot have implementations. ... An abstract class may contain non-final variables. Members of a Java interface are public by default. A Java abstract class can have the usual flavors of class members like private, protected, etc..
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Abstract methods are declared in abstract classes and cannot be implemented in the same class. ... A non-abstract method is a concrete method. With the exception of the instance constructor, concrete instance methods of a class can also call their abstract methods. Final methods can no longer be redefined in subclasses.
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Main difference is methods of a Java interface are implicitly abstract and cannot have implementations. ... Variables declared in a Java interface is by default final. An abstract class may contain non-final variables. Members of a Java interface are public by default.
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Main difference is methods of a Java interface are implicitly abstract and cannot have implementations. A Java abstract class can have instance methods that implements a default behavior. Variables declared in a Java interface is by default final. An abstract class may contain non-final variables.
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An abstract class is a class that is declared abstract —it may or may not include abstract methods. Abstract classes cannot be instantiated, but they can be subclassed. When an abstract class is subclassed, the subclass usually provides implementations for all of the abstract methods in its parent class.
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Main difference is methods of a Java interface are implicitly abstract and cannot have implementations. A Java abstract class can have instance methods that implements a default behavior. ... An abstract class may contain non-final variables. Members of a Java interface are public by default.
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An interface can extend another Java interface only, an abstract class can extend another Java class and implement multiple Java interfaces. ... A Java class can implement multiple interfaces but it can extend only one abstract class.
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From Java 8, it can have default and static methods also. ... Type of variables: Abstract class can have final, non-final, static and non-static variables. Interface has only static and final variables. Implementation: Abstract class can provide the implementation of interface.
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The main difference between the two is that with the Abstract Factory pattern, a class delegates the responsibility of object instantiation to another object via composition whereas the Factory Method pattern uses inheritance and relies on a subclass to handle the desired object instantiation. the instantiation!