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

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| 00:01
 
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|  Welcome to the''' Spoken Tutorial''' on''' Java Interfaces'''
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|  Welcome to the''' Spoken Tutorial''' on''' Java Interfaces'''.
  
 
|-
 
|-
 
| 00:05
 
| 00:05
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|  In this tutorial we will learn about: Creating an''' interface'''
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|  In this tutorial, we will learn about: * Creating an''' interface'''
  
 
|-
 
|-
 
|  00:10
 
|  00:10
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| Creating an''' Implementation classes''' and Usage of  Interface'''
+
| * Creating ''' Implementation classes''' and * Usage of  Interface'''.
  
 
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| 00:16
 
| 00:16
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|  For this tutorial, I am using
+
|  For this tutorial, I am using:
 +
 
 
'''Ubuntu 12.04'''
 
'''Ubuntu 12.04'''
 +
 
'''JDK 1.7 '''and
 
'''JDK 1.7 '''and
 +
 
'''Eclipse 4.3.1'''
 
'''Eclipse 4.3.1'''
  
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|  00:42
 
|  00:42
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|If not, for relevant''' Java''' tutorials, please visit the link shown.
+
|If not, for relevant Java tutorials, please visit the link shown.
  
 
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|-
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|-
 
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| 00:52
 
| 00:52
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| An''' Interface''' contains a set of''' abstract''' '''methods''' and''' static data members'''.
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| An Interface contains a set of''' abstract''' methods and''' static data members'''.
  
 
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|-
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|-
 
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|  01:15
 
|  01:15
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|Here we will create the necessary''' classes''' and''' interface''' to demonstrate the usage of''' interfaces.'''
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|Here, we will create the necessary''' classes''' and''' interface''' to demonstrate the usage of''' interfaces.'''
  
 
|-
 
|-
 
| 01:24
 
| 01:24
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| Right click on''' src''' folder and click''' New-'''>''' Interface'''.
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| Right-click on''' src''' folder and click''' New > Interface'''.
  
 
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|  01:34
 
|  01:34
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|Note that the '''“interface”''' keyword is used for defining an '''interface'''.
+
|Note that the '''“interface”''' keyword is used for defining an interface.
  
 
|-
 
|-
 
|  01:39
 
|  01:39
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|Now type the code as displayed on the screen
+
|Now type the code as displayed on the screen.
  
 
|-
 
|-
 
| 01:43
 
| 01:43
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| Here the the '''interface''' name is''' Animal.'''
+
| Here, the '''interface''' name is''' Animal.'''
  
 
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|-
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|-
 
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|  02:04
 
|  02:04
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|Here, the constant string value''' “Mammal”''' is assigned to the variable''' “type1”'''.
+
|Here, the constant string value “Mammal” is assigned to the variable “type1”.
  
 
|-
 
|-
 
|  02:12
 
|  02:12
−
|And''' “Reptiles”''' is assigned to the variable''' “type2”'''.
+
|And “Reptiles” is assigned to the variable “type2”.
  
 
|-
 
|-
 
|  02:16
 
|  02:16
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|All''' constant values''' defined in an''' interface''' are implicitly''' public, static''' and''' final.'''
+
|All''' constant''' values defined in an''' interface''' are implicitly''' public, static''' and''' final.'''
  
 
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|-
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|-
 
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| 02:32
 
| 02:32
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| Here''' Human''' is a''' class''' which implements the''' Animal interface.'''
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| Here,''' Human''' is a class which implements the''' Animal''' interface.
  
 
|-
 
|-
 
|  02:38
 
|  02:38
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|So it must provide implementations for the methods''' talk(), see()''' and''' move().'''
+
|So, it must provide implementations for the methods''' talk(), see()''' and''' move().'''
  
 
|-
 
|-
 
|02:45
 
|02:45
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| A '''class''' can also implement''' multiple interfaces'''.
+
| A '''class''' can also implement multiple interfaces.
  
 
|-
 
|-
 
|  02:49
 
|  02:49
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|As shown in the example, the''' class Human implements''' two''' interfaces Animal''' and''' Action.'''
+
|As shown in the example, the class '''Human''' implements two interfaces '''Animal''' and''' Action.'''
  
 
|-
 
|-
 
|  02:57
 
|  02:57
−
|Note that a''' comma operator''' used in the syntax is to identify the different''' interfaces.'''
+
|Note that a''' comma operator''' used in the syntax is to identify the different interfaces.  
  
 
|-
 
|-
 
|  03:04
 
|  03:04
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|Now this''' class''' should provide implementations to all the''' abstract methods''' in both''' Animal''' and''' Action interfaces.'''
+
|Now this''' class''' should provide implementations to all the''' abstract methods''' in both''' Animal''' and''' Action''' interfaces.
  
 
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|-
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|-
 
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|  03:18
 
|  03:18
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|The''' Animal class''' is an''' interface.'''
+
|The''' Animal''' class is an''' interface.'''
  
 
|-
 
|-
 
|  03:22
 
|  03:22
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|The''' Human''' and''' Snake classes''' are the two '''implementation classes.'''
+
|The''' Human''' and''' Snake''' classes are the two '''implementation classes.'''
  
 
|-
 
|-
 
|  03:28
 
|  03:28
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|The '''Human class''' provides its own different implementations for''' talk()''',''' see()''' and''' move() methods.'''
+
|The '''Human''' class provides its own different implementations for''' talk()''',''' see()''' and''' move()''' methods.
  
 
|-
 
|-
 
|  03:36
 
|  03:36
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|And the '''Snake class''' provides its own different implementations for '''talk(), see()''' and '''move() methods'''.
+
|And, the '''Snake''' class provides its own different implementations for '''talk(), see()''' and '''move()''' methods.
  
 
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|-
 
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| 03:50
 
| 03:50
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|  Right click on the '''default package''' and create a''' class''' called''' Human.'''
+
|  Right-click on the '''default package''' and create a''' class''' called''' Human.'''
  
 
|-
 
|-
 
|  03:56
 
|  03:56
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|Now, to make this an '''implementation class''' of''' Animal, '''type''' implements Animal'''
+
|Now, to make this an '''implementation class''' of''' Animal''', type: '''implements Animal'''.
  
 
|-
 
|-
 
|  04:04
 
|  04:04
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|  Now we can see an error comes up in the''' Eclipse IDE.'''  
+
|  Now, we can see an error comes up in the''' Eclipse IDE.'''  
  
 
|-
 
|-
 
|  04:09
 
|  04:09
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|This error indicates that, we should provide an '''implementation''' to the '''Animal interface.'''
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|This error indicates that we should provide an '''implementation''' to the '''Animal interface.'''
  
 
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| 04:19
 
| 04:19
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|  Now let us define the''' methods talk(), see()''' and''' move().'''
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|  Now let us define the methods '''talk(), see()''' and''' move().'''
  
 
|-
 
|-
 
|  04:23
 
|  04:23
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|So type''' public void talk( )''' within curly brackets type '''System.''out''.println''' within quotes''' I am a human and I belong to'''
+
|So, type:''' public void talk( )''' within curly brackets type '''System.out.println''' within quotes "I am a human and I belong to".
  
 
|-
 
|-
 
|  04:37
 
|  04:37
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|Now we can use the value of the''' static, final variable type1''' declared in the''' Animal interface'''
+
|Now we can use the value of the''' static, final variable type1''' declared in the''' Animal''' interface.
  
 
|-
 
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|  04:45
 
|  04:45
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|So type, '''+ Animal.type1+''' within quotes''' family '''semicolon.
+
|So, type: '''+ Animal.type1+''' within quotes "family" semicolon.
  
 
|-
 
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|  04:54
 
|  04:54
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|Let us now implement the '''see() method'''.
+
|Let us now implement the '''see()''' method.
  
 
|-
 
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|  04:57
 
|  04:57
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|So type''' public void see( )''' within curly brackets type '''System.''out''.println''' within quotes''' I can see all colors''' semicolon
+
|So, type:''' public void see( )''' within curly brackets type '''System.out.println''' within quotes "I can see all colors" semicolon.
  
 
|-
 
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|  05:11
 
|  05:11
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|We should also define the''' move() method'''.
+
|We should also define the''' move()''' method.
  
 
|-
 
|-
 
|  05:14
 
|  05:14
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|So type''' public void move( ).''' within curly brackets type '''System.''out''.println''' within quotes''' I move by walking''' semicolon
+
|So, type:''' public void move( )''' within curly brackets type '''System.out.println''' within quotes "I move by walking" semicolon.
  
 
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|  05:34
 
|  05:34
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|  Next we will see how to define the''' Snake class.'''
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|  Next we will see how to define the''' Snake''' class.
  
 
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| 05:52
 
| 05:52
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|  We can see that all the '''methods''' of the''' Animal interface talk()''' ,''' see()''' and''' move()''' are implemented inside this '''class'''.
+
|  We can see that all the '''methods''' of the''' Animal interface- talk(), see()''' and''' move()''' are implemented inside this '''class'''.
  
 
|-
 
|-
 
|  06:01
 
|  06:01
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|Here the''' talk() method''' prints “'''I am a snake and I belong to”'''
+
|Here, the''' talk()''' method prints “I am a snake and I belong to”.
  
 
|-
 
|-
 
|  06:07
 
|  06:07
−
|Then the value of''' Animal.type2''' is to be printed and then''' “family”'''
+
|Then the value of''' Animal.type2''' is to be printed and then “family”.
  
 
|-
 
|-
 
|  06:13
 
|  06:13
−
|Here the''' see() method''' prints “'''I can see only in black and white”'''
+
|Here, the''' see()''' method prints “I can see only in black and white”.
  
 
|-
 
|-
 
|  06:19
 
|  06:19
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|The''' move() method''' prints''' "I move by crawling"'''
+
|The''' move()''' method prints "I move by crawling".
  
 
|-
 
|-
 
| 06:23
 
| 06:23
−
|  Note that the''' Human class''' has its own implementations of''' talk(), see()''' and''' move() methods'''.
+
|  Note that the''' Human''' class has its own implementations of''' talk(), see()''' and''' move()''' methods.
  
 
|-
 
|-
 
|  06:31
 
|  06:31
−
|And the''' Snake class''' has its own implementations of''' talk(), see()''' and''' move() methods'''.
+
|And, the''' Snake''' class has its own implementations of''' talk(), see()''' and''' move()''' methods.
  
 
|-
 
|-
 
|  06:39
 
|  06:39
−
|  Now right click on the default package click''' new'''->''' class''' and then type the name as''' Demo.'''
+
|  Now, right-click on the default package, click''' new > class''' and then type the name as''' Demo.'''
  
 
|-
 
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|  06:47
 
|  06:47
−
|Inside this '''class''' we will have the''' main method''',
+
|Inside this '''class''', we will have the''' main''' method.
  
 
|-
 
|-
 
|  06:51
 
|  06:51
−
|So type''' main''' and then press ctrl+space to generate the''' main method.'''
+
|So, type''' main''' and then press '''ctrl+space''' to generate the''' main''' method.
  
 
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|  07:01
 
|  07:01
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|In this line we instantiate the ''' Human class''' using the''' Animal interface.'''
+
|In this line, we instantiate the ''' Human class''' using the''' Animal''' interface.
  
 
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|  07:14
 
|  07:14
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|Now we can invoke the different '''methods''' using this '''object''' as '''h.talk()''', '''h.see();'''
+
|Now we can invoke the different methods using this '''object''' as '''h.talk(); h.see();   h.move();'''
−
'''h.move();'''
+
  
 
|-
 
|-

Revision as of 16:47, 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 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 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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