[PDF] Polymorphism through the Java Interface PDF 05-PolymorphismViaInterfaces.pdf

To understand polymorphism, take an example of a workday at Franklin, Beedle, and Associates Kim brought in pastries while everyone was chatting When

In the example below polymorphism is demonstrated by the use of multiple add methods The computer differentiates among them by the method signatures (the

[PDF] Chapter 13 Inheritance and Polymorphism

For example, in the vehicle domain we could implement a Vehicle superclass as follows Vehicle java 1 2 3 4 5 6 7

[PDF] Java - Polymorphism - Tutorialspoint

Polymorphism is the ability of an object to take on many forms Now, the Deer class is considered to be polymorphic since this has multiple inheritance Deer d = new Deer(); Animal a = d; Vegetarian v = d; Object o = d;

[PDF] Inheritance and Polymorphism - Fas Harvard - Harvard University

Example: our Taxi class can define its own toString method: public String Inheritance in the Java API The name for this feature of Java is polymorphism

[PDF] Polymorphism through the Java Interface

To understand polymorphism, take an example of a workday at Franklin, Beedle, and Associates Kim brought in pastries while everyone was chatting When

[PDF] Polymorphism

Poly- morphism occurs in Java through the difference between the declared static class of a variable and the actual dynamic class of the value the variable

[PDF] Chapter 9: Polymorphism Lab Exercises

Polymorphism via Inheritance Another Firm java Author: Lewis/Loftus // // Demonstrates polymorphism via For example, create a list, print it, and search for

[PDF] Polymorphism

Polymorphism A deeper look into Lets have a look at some examples java lang Object contains methods that all classes inherit ○ These include: ○ clone

[PDF] Object- Oriented Programming: Polymorphism - Pearsoncmgcom

Consider the following example of polymorphism Suppose we 10 7 8 Common Interfaces of the Java API performed due to Java's polymorphic capabilities

[PDF] POLYMORPHISM

In software, polymorphism refers to a method that has different implementations in different subclasses of a class hierarchy This allows you to create a subclass

[PDF] polymorphism in java example javatpoint

[PDF] polymorphism java example stackoverflow

[PDF] polynesie 2016 maths es

[PDF] polynésie 2016 maths es corrigé

[PDF] polynésie juin 2016 maths corrigé es

[PDF] polynesie juin 2016 maths s

[PDF] polynôme caractéristique

[PDF] polynome et fraction rationnelle cours

[PDF] polynomial lens distortion model

[PDF] polynomial solution

[PDF] polynomials and conjugate roots

[PDF] polynomials class 9 worksheet pdf

[PDF] polyphemus pronunciation

[PDF] polypnée definition arabe

[PDF] polypnée définition larousse

1

Polymorphism through the

Java Interface

Rick Mercer

Outline

Describe Polymorphism

Show a few ways that interfaces are used

Compare objects with Comparator

Create our own icons with Icon

Play audio files with AudioClip

The role of interfaces in Javas Collection Framework 3

Polymorphism

In general, polymorphism is the ability to appear in many forms

In object-oriented programming, polymorphism

refers to a programming language's ability to process objects differently depending on their data type (class) Polymorphism is a requirement of any true object- oriented programming language 4

Polymorphism from mercer

To understand polymorphism, take an example of a

workday at Franklin, Beedle, and Associates. Kim brought in pastries while everyone was chatting. When the food was mostly devoured, Jim, the president of the company, invited everyone to 䇾Get back to work.䇿 Sue went back to read a new section of a book she was editing. Tom continued laying out a book. Stephanie went back to figure out some setting in her word- processing program. Ian finished the company catalog. 5

Polymorphism

Jeni met with Jim to discuss a new project. Chris began contacting professors to review a new manuscript. And Krista continued her Web search to find on whether colleges are using C++, Python, or Java. Marty went back to work on the index of his new book. Kim cleaned up the pastries. Rick was just visiting so he went to work on the remaining raspberries. 6

Polymorphic Messages

10 different behaviors with the same message!

The message 䇾Get back to work䇿is a

polymorphic message a message that is understood by many different types of object (or employees in this case) but responded to with different behaviors based on the type of the employee: Editor, Production, 7

Polymorphism

Polymorphism allows the same message to be

sent to different types to get different behavior

In Java, polymorphism is possible through

inheritance Example: Override toString()to return different values that are textual representations of that type. interfaces

Example: Collections.sort(List)sends

compareTomessages to objects that must have implemented Comparable 8

Polymorphism

The runtime message finds the correct method

same message can invoke different methods the reference variable knows the type aString.compareTo(anotherString) anInteger.compareTo(anotherInteger) aButton.actionPerformed(anEvent) aTextField.actionPerformed(anEvent) aList.add(anObject) aHashSet.add(anObject) 9

The Java Interface

An interface describes a set of methods

class variables are allowed (need static)

NOT allowed: constructors, instance variables

publicinterfaceIBowlingLine{ publicstaticfinalintLAST_FRAME= 10; publicabstractintscoreAtFrame(intframe); public intscoreSoFar(); // Interface methods are implicitly abstract, so the // abstract modifier is not used with interface methods // (it could be²it's just not necessary). // Also public by default, so this would work voidpinsDowned(int pins); 10

The Java Interface

Interfaces are to be implemented by a class

~ 33% of classes (about 1,000) in Javas API implement one or more interfaces

Typically, two or more classes implement the

same interface

Type guaranteed to have the same methods

Objects can be treated as the same type

May use different algorithms / instance variables

/ data structures 11

The Comparable interface

remember? Can assign an instance of a class that implements and interface to a variable of the interface type

Comparable str = newString("abc");

Comparable acct = newBankAccount("B", 1);

Comparable day = newDate();

Some classes implement Comparable

find out how many with Javas API interface Comparable defines the "natural ordering" for collections 12 interface comparator * Compares its two arguments for order. Returns a * negative integer, zero, or a positive integer as the * first argument is less than, equal to, or greater * than the second argument. Equals not shown here publicinterfaceComparator { intcompare(T one, T other); Can specify sort order by objects. In the code below

What class needs to be written?

What interface must that new class implement?

Comparator idComparator= newByID();

Collections.sort(accounts, idComparator);

Sort using different Comparators

13 class OurIcon implements Icon

Icon myIcon= new

JOptionPane.showMessageDialog(

null, "View from\nthe UofA\nComputer Science\nDepartment", "Message",

JOptionPane.INFORMATION_MESSAGE,

myIcon); Notice the 5thparameter type, class or interface? public static void showMessageDialog(ComponentparentComponent, Objectmessage, Stringtitle, intmessageType,Iconicon) throws HeadlessException 14

LiveCamImage

publicclassLiveCamImage implementsIcon { privateBufferedImage myImage; publicLiveCamImage(String imageFileName) { try{ myImage= } catch(IOException e) { System.err.println("Could not load"+ imageFileName); // Control the upper left corner of the image publicvoidpaintIcon(Component c, Graphics g, intx, inty) { g.drawImage(myImage, 2, 2, null); // Icon also specifies getIconWidth and getIconHeight // See file in InterfaceExamples.zip 15

An interface you need now

An interface, a reference type, can have

staticvariables and method headings with ; publicintsize(); // no { }

Many classes may implement an interface

Use interface ActionListenerto register any

number of objects to respond to button clicks, menu selections, and input into a text field public interfaceActionListener{ public void actionPerformed(ActionEventtheEvent); 16

Multiple classes implement

the same interface

To implement an interface, classes must have

all methods specified as given in the interface privateclassTheButtonListener implements ActionListener { publicvoidactionPerformed(ActionEvent theEvent) { // Do this method when a user clicks TheButton private classTheTextFieldListener implements ActionListener {

public void actionPerformed(ActionEvent theEvent) {// Do this code when user presses the enter // key in TheTextField when it has focus}}

quotesdbs_dbs19.pdfusesText_25

[PDF] [PDF] Polymorphism through the Java Interface

Polymorphism through the

Java Interface

Rick Mercer

Outline

Describe Polymorphism

Show a few ways that interfaces are used

Compare objects with Comparator

Create our own icons with Icon

Play audio files with AudioClip

Polymorphism

In object-oriented programming, polymorphism

Polymorphism from mercer

To understand polymorphism, take an example of a

Polymorphism

Polymorphic Messages

10 different behaviors with the same message!

The message 䇾Get back to work䇿is a

Polymorphism

Polymorphism allows the same message to be

In Java, polymorphism is possible through

Example: Collections.sort(List)sends

Polymorphism

The runtime message finds the correct method

The Java Interface

An interface describes a set of methods

NOT allowed: constructors, instance variables

The Java Interface

Interfaces are to be implemented by a class

Typically, two or more classes implement the

Type guaranteed to have the same methods

Objects can be treated as the same type

May use different algorithms / instance variables

The Comparable interface

Comparable str = newString("abc");

Comparable acct = newBankAccount("B", 1);

Comparable day = newDate();

Some classes implement Comparable

What class needs to be written?

What interface must that new class implement?

Comparator idComparator= newByID();

Collections.sort(accounts, idComparator);

Sort using different Comparators

Icon myIcon= new

JOptionPane.showMessageDialog(

JOptionPane.INFORMATION_MESSAGE,

LiveCamImage

An interface you need now

An interface, a reference type, can have

Many classes may implement an interface

Use interface ActionListenerto register any

Multiple classes implement

To implement an interface, classes must have

Describe Polymorphism

Show a few ways that interfaces are used

In object-oriented programming, polymorphism

10 different behaviors with the same message!

The message 䇾Get back to work䇿is a

Polymorphism allows the same message to be

In Java, polymorphism is possible through

Example: Collections.sort(List)sends

The runtime message finds the correct method

An interface describes a set of methods

Interfaces are to be implemented by a class

Typically, two or more classes implement the

Some classes implement Comparable

An interface, a reference type, can have

Many classes may implement an interface

To implement an interface, classes must have