Difference between revisions of "Java/C3/Java-Interfaces/English-timed"

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|  07:26
 
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|  Next, we instantiate the''' Snake class''' using the''' Animal interface'''
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|  Next, we instantiate the''' Snake''' class using the''' Animal''' interface.
  
 
|-
 
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|  07:31
 
|  07:31
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|Now we can invoke the different '''methods''' using this '''object''' as shown
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|Now we can invoke the different methods using this '''object''' as shown.
  
 
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|  07:38
 
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|  Now let us run this''' Demo''' program.
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|  Now, let us '''run''' this''' Demo''' program.
  
 
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|  07:41
 
|  07:41
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|  So right click on the'' class''''' Demo''' and then select''' Run as''' ->''' Java Application'''
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|  So, right-click on the class ''' Demo''' and then select''' Run as > Java Application'''.
  
 
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|  We can see the output  
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|  We can see the output.
  
 
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|  07:52
 
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|These are printed by the''' talk(), see()''' and''' move() methods''' invoked using the''' human class object h'''
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|These are printed by the''' talk(), see()''' and''' move()''' methods invoked using the''' human class object h'''.
  
 
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|  08:00
 
|  08:00
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|  These are printed by the''' talk(), see()''' and''' move() methods''' invoked using  the''' Snake class object s'''
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|  These are printed by the''' talk(), see()''' and''' move()''' methods invoked using  the''' Snake class object s'''.
  
 
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| 08:08
 
| 08:08
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| Now let us explore the differences between an''' interface''' and an''' abstract class'''.
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| Now, let us explore the differences between an''' interface''' and an''' abstract class'''.
  
 
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|08:14
 
|08:14
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| All the methods in an''' interface''' should be''' abstract.'''
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| All the methods in an interface should be''' abstract.'''
  
 
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|Within''' interface''' there should not be any  '''constructors'''
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|Within interface, there should not be any  '''constructors''',
  
 
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|  08:23
 
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| '''concrete methods''',  '''static methods '''and '''main method'''
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| '''concrete methods''',  '''static methods '''and '''main method'''.
  
 
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|The variables in an''' interface''' should be''' static''' and''' final.'''  
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|The variables in an interface should be''' static''' and''' final.'''  
  
 
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|  In this tutorial we have learnt about - Creating an''' Interface'''
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|  In this tutorial, we have learnt about: * Creating an''' Interface'''
  
 
|-
 
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|  08:53
 
|  08:53
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| Creating an''' implementation class''' and
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| * Creating an''' implementation class''' and
  
 
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|  08:56
 
|  08:56
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| Usage of''' interfaces'''
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|* Usage of''' interfaces'''.
  
 
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|  08:59
 
|  08:59
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|  As an''' assignment''' Create an '''interface Vehicle''' which contains the '''methods brake()''' and''' run()'''
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|  As an assignment, create an interface '''Vehicle''' which contains the methods '''brake()''' and''' run()'''.
  
 
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|  09:07
 
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|  Create another '''interface Fuel''' which contains the following '''methods'''.  '''fill(String type,int quantity)''' , '''pay(int quantity,int price)'''
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|  Create another interface '''Fuel''' which contains the following methods.  '''fill(String type,int quantity)''', '''pay(int quantity,int price)'''.
  
 
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|Here''' brake method''' should print''' ”Car Applies Power brake”'''
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|Here,''' brake''' method should print "Car Applies Power brake".
  
 
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|  09:30
 
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|And the '''run method''' must print''' ”Car is running on 4 wheels”'''
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|And the '''run''' method must print "Car is running on 4 wheels".
  
 
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|  09:35
 
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|  Similarly''' fill() method''' can print the type and quantity of the fuel filled.
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|  Similarly''' fill()''' method can print the type and quantity of the fuel filled.
  
 
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|  09:41
 
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|For example: 10 Litres of Petrol.
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|For example: 10 Litres of petrol.
  
 
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|  09:44
 
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|  '''pay() method''' can be used to print price to be paid. For example: Pay Rs. 640
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|  '''pay()''' method can be used to print price to be paid. For example: Pay Rs. 640
  
 
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| 09:53
 
| 09:53
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|Create another subclass''' Bike''' which again implements both the '''interfaces Vehicle''' and''' Fuel'''
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|Create another subclass''' Bike''' which again implements both the interfaces '''Vehicle''' and''' Fuel'''.
  
 
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|  10:00
 
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|Here '''brake method''' can print ”'''Bike Applies hand brake”'''
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|Here, '''brake''' method can print "Bike Applies hand brake".
  
 
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|  10:05
 
|  10:05
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|And the '''run method''' can print “'''Bike is running on 2 wheels”'''
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|And the '''run''' method can print “Bike is running on 2 wheels”.
  
 
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|  10:10
 
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|Next implement the '''fill()''' and '''pay() methods''' as explained earlier.
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|Next, implement the '''fill()''' and '''pay()''' methods as explained earlier.
  
 
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|  10:15
 
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|Finally create a '''Demo class''' containing the '''main method''' to verify the results.
+
|Finally create a '''Demo class''' containing the '''main''' method to verify the results.
  
 
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|  10:21
 
|  10:21
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|  This video at the following link summarizes the''' Spoken Tutorial Project.''' Please download and watch it.
+
|  This video at the following link summarizes the Spoken Tutorial Project. Please download and watch it.
  
 
|-
 
|-
 
| 10:29
 
| 10:29
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|  The''' Spoken Tutorial Project Team''' ,  Conducts workshops using spoken tutorials and Gives certificates on passing the online tests.
+
|  The Spoken Tutorial Project Team:
 +
* Conducts workshops using spoken tutorials and  
 +
* Gives certificates on passing the online tests.
  
 
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|More information on this Mission is available at the link shown.
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|More information on this mission is available at the link shown.
  
 
|-
 
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|  10:52
 
|  10:52
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|This script has been contributed by: '''Deptartment of Information''' '''Technology, Amal Jyothi College of Engineering'''
+
|This script has been contributed by: Department of Information Technology, Amal Jyothi College of Engineering.
  
 
|-
 
|-
 
|  11:01
 
|  11:01
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|This is Priya from IIT Bombay signing off. Thanks for joining.
+
|This is Priya from '''IIT Bombay''', signing off. Thanks for joining.
  
 
|}
 
|}

Revision as of 16:02, 18 May 2017

Time
Narration
00:01 Welcome to the Spoken Tutorial on Java Interfaces
00:05 In this tutorial we will learn about: Creating an interface
00:10 Creating an Implementation classes and Usage of Interface
00:16 For this tutorial, I am using

Ubuntu 12.04 JDK 1.7 and Eclipse 4.3.1

00:28 To follow this tutorial, you should have knowledge of basics of Java and Eclipse IDE.
00:36 You should also have the knowledge of subclassing and Abstract classes in Java.
00:42 If not, for relevant Java tutorials, please visit the link shown.
00:48 First let's understand what is an interface.
00:52 An Interface contains a set of abstract methods and static data members.
00:58 It defines the signatures of a set of methods without the body.
01:04 It is declared using the interface keyword.
01:08 Now we will switch to Eclipse and create a new project called InterfaceDemo.
01:15 Here we will create the necessary classes and interface to demonstrate the usage of interfaces.
01:24 Right click on src folder and click New-> Interface.
01:30 Type the name as Animal and press Enter.
01:34 Note that the “interface” keyword is used for defining an interface.
01:39 Now type the code as displayed on the screen
01:43 Here the the interface name is Animal.
01:46 It contains three abstract methods talk(), see() and move().
01:52 All such methods in an interface are implicitly public and abstract.
01:59 An interface can also contain constant variable declarations.
02:04 Here, the constant string value “Mammal” is assigned to the variable “type1”.
02:12 And “Reptiles” is assigned to the variable “type2”.
02:16 All constant values defined in an interface are implicitly public, static and final.
02:25 Next we will see implementation class for an interface with an example.
02:32 Here Human is a class which implements the Animal interface.
02:38 So it must provide implementations for the methods talk(), see() and move().
02:45 A class can also implement multiple interfaces.
02:49 As shown in the example, the class Human implements two interfaces Animal and Action.
02:57 Note that a comma operator used in the syntax is to identify the different interfaces.
03:04 Now this class should provide implementations to all the abstract methods in both Animal and Action interfaces.
03:13 The figure here represents an implement relation.
03:18 The Animal class is an interface.
03:22 The Human and Snake classes are the two implementation classes.
03:28 The Human class provides its own different implementations for talk(), see() and move() methods.
03:36 And the Snake class provides its own different implementations for talk(), see() and move() methods.
03:45 Let us understand the usage of interfaces with a sample program.
03:50 Right click on the default package and create a class called Human.
03:56 Now, to make this an implementation class of Animal, type implements Animal
04:04 Now we can see an error comes up in the Eclipse IDE.
04:09 This error indicates that, we should provide an implementation to the Animal interface.
04:15 Let us see how to rectify this error.
04:19 Now let us define the methods talk(), see() and move().
04:23 So type public void talk( ) within curly brackets type System.out.println within quotes I am a human and I belong to
04:37 Now we can use the value of the static, final variable type1 declared in the Animal interface
04:45 So type, + Animal.type1+ within quotes family semicolon.
04:54 Let us now implement the see() method.
04:57 So type public void see( ) within curly brackets type System.out.println within quotes I can see all colors semicolon
05:11 We should also define the move() method.
05:14 So type public void move( ). within curly brackets type System.out.println within quotes I move by walking semicolon
05:29 Note that the error disappears, once all the methods are implemented.
05:34 Next we will see how to define the Snake class.
05:38 I have already created it in my project.
05:42 Please create the snake class in your project and type the following code as displayed on the screen.
05:49 Now let us go through the code.
05:52 We can see that all the methods of the Animal interface talk() , see() and move() are implemented inside this class.
06:01 Here the talk() method prints “I am a snake and I belong to”
06:07 Then the value of Animal.type2 is to be printed and then “family”
06:13 Here the see() method prints “I can see only in black and white”
06:19 The move() method prints "I move by crawling"
06:23 Note that the Human class has its own implementations of talk(), see() and move() methods.
06:31 And the Snake class has its own implementations of talk(), see() and move() methods.
06:39 Now right click on the default package click new-> class and then type the name as Demo.
06:47 Inside this class we will have the main method,
06:51 So type main and then press ctrl+space to generate the main method.
06:58 Type the following code as displayed on the screen.
07:01 In this line we instantiate the Human class using the Animal interface.
07:07 This is represented as Animal h equals new Human();
07:14 Now we can invoke the different methods using this object as h.talk(), h.see();

h.move();

07:26 Next, we instantiate the Snake class using the Animal interface.
07:31 Now we can invoke the different methods using this object as shown.
07:38 Now, let us run this Demo program.
07:41 So, right-click on the class Demo and then select Run as > Java Application.
07:48 We can see the output.
07:52 These are printed by the talk(), see() and move() methods invoked using the human class object h.
08:00 These are printed by the talk(), see() and move() methods invoked using the Snake class object s.
08:08 Now, let us explore the differences between an interface and an abstract class.
08:14 All the methods in an interface should be abstract.
08:18 Within interface, there should not be any constructors,
08:23 concrete methods, static methods and main method.
08:28 But an abstract class can have all these inside it.
08:32 The variables in an interface should be static and final.
08:38 There are no such restrictions for an abstract class.
08:43 This brings us to the end of this tutorial. Let us summarize.
08:48 In this tutorial, we have learnt about: * Creating an Interface
08:53 * Creating an implementation class and
08:56 * Usage of interfaces.
08:59 As an assignment, create an interface Vehicle which contains the methods brake() and run().
09:07 Create another interface Fuel which contains the following methods. fill(String type,int quantity), pay(int quantity,int price).
09:19 Create a subclass Car which implements both interfaces Vehicle and Fuel.
09:26 Here, brake method should print "Car Applies Power brake".
09:30 And the run method must print "Car is running on 4 wheels".
09:35 Similarly fill() method can print the type and quantity of the fuel filled.
09:41 For example: 10 Litres of petrol.
09:44 pay() method can be used to print price to be paid. For example: Pay Rs. 640
09:53 Create another subclass Bike which again implements both the interfaces Vehicle and Fuel.
10:00 Here, brake method can print "Bike Applies hand brake".
10:05 And the run method can print “Bike is running on 2 wheels”.
10:10 Next, implement the fill() and pay() methods as explained earlier.
10:15 Finally create a Demo class containing the main method to verify the results.
10:21 This video at the following link summarizes the Spoken Tutorial Project. Please download and watch it.
10:29 The Spoken Tutorial Project Team:
  • Conducts workshops using spoken tutorials and
  • Gives certificates on passing the online tests.
10:38 For more details, please write to us.
10:41 Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India.
10:48 More information on this mission is available at the link shown.
10:52 This script has been contributed by: Department of Information Technology, Amal Jyothi College of Engineering.
11:01 This is Priya from IIT Bombay, signing off. Thanks for joining.

Contributors and Content Editors

PoojaMoolya, Pratik kamble, Sandhya.np14

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