Interfaces • Java does not support multiple inheritance • What if we want an object Interface • A special type of class - a “pure” abstract class: • No data ( only
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If a class implements an interface, it must provide bodies for all methods — otherwise it must be an “abstract” class (more later) An interface can extend other interfaces A class can extend only one class, but it can implement many interfaces
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Abstract classes cannot be instantiated – Instantiate (v ) – use the “new” keyword to create a new Object (or instance of a class)
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class ▻ If a subclass of an abstract superclass does not implement all the abstract methods, the In many ways, an interface is similar to an abstract class,
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An interface can be implemented by multiple classes • Each implementing class can provide their own unique versions of the method definitions interface I1 { void
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Abstract classes are permitted to contain implementations for some methods while interfaces are not • To implement the type defined by an abstract class, a class
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An abstract class is a way for parent classes to guarantee that child classes provide an implementation for a specific method › Consider the Shape example
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public class C extends B { public int two() { } public String three() { } } 20 CISC 124, Winter 2016, Topic 5: Abstract Classes Interfaces • An abstract class is not
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public abstract class GeometricObject { private String color = "white"; private boolean filled; private java util Date dateCreated; protected GeometricObject() {
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1) Abstract class can have abstract and non- abstract methods Interface can have only abstract methods Since Java 8 it can have default and static
Abstract Classes and Abstract Methods An interface is treated like a special class in Java: Uses of interfaces are like for abstract classes:
Interface • A special type of class - a “pure” abstract class: • No data (only static or final) • Defines a set of abstract methods (prototypes)
Abstract classes and Interfaces ? Difference between extends and implements ? Multiple inheritance ? Comparator and Comparable ? Comparing objects
State design pattern; evaluation of functions with JEval; interface specification for a spreadsheet; class diagram hierarchy and modeling for an interconnect
An interface establishes a set of methods that a class will implement • Similar to abstract class but all methods are abstract (and all properties are
CS61B Lecture #9: Interfaces and Abstract Classes Recreation Show that for any polynomial with a leading coefficient of 1 and integral
We will first learn what an abstract class and interface is We will also do a detailed comparison of interfaces and abstract classes followed by a listing
[PDF] Example of abstract class and interface in Java - Pragjyotish College