what is difference between interface and abstract class in java?
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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. ... A Java class can implement multiple interfaces but it can extend only one abstract class.
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In interfaces, you can define the same components as in classes. You cannot assign the components of an interface explicitly to a visibility section, because interface components always extend the public area of a class when they are implemented in it.
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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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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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An abstract class may contain non-final variables. Type of variables: Abstract class can have final, non-final, static and non-static variables. ... Multiple implementation: An interface can extend another Java interface only, an abstract class can extend another Java class and implement multiple Java interfaces.
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In Java , interface doesn't allow you to declare any instance variables. Using a variable declared in an interface as an instance variable will return a compile time error. You can declare a constant variable, using static final which is different from an instance variable.
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Interfaces are completely empty shells that expect child classes to implement everything for them. On the other hand, abstract class can not only contain common piece of information by implementing inside them but also expect child classes to fill in the remaining gaps.
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A static variable is a class variable. A single copy of the static variable is created for all instances of the class. It can be directly accessed in a static method. An abstract class in Java is a class that cannot be instantiated.
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In summary, virtual classes permits subclassing and method overriding. However, a virtual class does implement functionality itself and can be instantiated and used directly. Conversely, abstract classes must be subclassed and have methods overridden to provide functionality.
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The difference between wrapper class and primitive type in Java is that wrapper class is used to convert a primitive type to an object and object back to a primitive type while a primitive type is a predefined data type provided by the Java programming language.
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Learn TypeScript the right way! A class is a blueprint from which we can create objects that share the same configuration - properties and methods. An interface is a group of related properties and methods that describe an object, but neither provides implementation nor initialisation for them.
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Interface represents the set of operations that a data structure supports. ... Implementation − Implementation provides the internal representation of a data structure. Implementation also provides the definition of the algorithms used in the operations of the data structure.
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Yes, an abstract class can have a constructor in Java. ... In order to use an abstract class in Java, You need to extend it and provide a concrete class. Abstract class is commonly used to define a base class for a type hierarchy with default implementation, which is applicable to all child classes.
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An interface contains behaviors that a class implements. A class may contain abstract methods, concrete methods. An interface contains only abstract methods. Members of a class can be public, private, protected or default.
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Dictionary is an abstract class in Java whereas Map is an interface. Since, Java does not support multiple inheritances, if a class extends Dictionary, it cannot extend any other class. Therefore, the Map interface was introduced. Dictionary class is obsolete and use of Map is preferred.
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The differences it highlights are the accessibility of data members and methods: abstract classes allow non-static and non-final fields and allow methods to be public, private, or protected while interfaces' fields are inherently public, static, and final, and all interface methods are inherently public.
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They are inheritance, polymorphism, abstraction and encapsulation. Inheritance and interfaces are related to OOP. The key difference between inheritance and interface is that inheritance is to derive new classes from existing classes and an interface is to implement abstract classes and multiple inheritance.