Difference between revisions of "Java/C2/Non-static-block/English-timed"

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|  00:02
 
|  00:02
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|  Welcome to the Spoken Tutorial on '''Non-static block '''in '''java'''.
+
|  Welcome to the Spoken Tutorial on '''Non-static block''' in '''java'''.
  
 
|-
 
|-
 
|  00:06
 
|  00:06
 
|  In this tutorial we will learn  
 
|  In this tutorial we will learn  
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|-
 
|-
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|-
 
|-
 
|  00:10
 
|  00:10
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|  When  a '''non-static block '''executed?
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|  When  a '''non-static block''' executed?
  
 
|-
 
|-
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|  00:16
 
|  00:16
 
|And Why we need '''constructors'''?
 
|And Why we need '''constructors'''?
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|-
 
|-
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* Java Development Environment jdk 1.6
 
* Java Development Environment jdk 1.6
 
*And  Eclipse IDE 3.7.0
 
*And  Eclipse IDE 3.7.0
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−
 
  
 
|-
 
|-
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|  00:38
 
|  00:38
 
| Now we will see what a '''non-static block''' is.
 
| Now we will see what a '''non-static block''' is.
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|-
 
|-
 
|  00:42
 
|  00:42
 
| Any code written between two curly brackets is a '''non-static block'''.
 
| Any code written between two curly brackets is a '''non-static block'''.
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|-
 
|-
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|  00:58
 
|  00:58
 
| It executes before the '''constructor''''s execution.
 
| It executes before the '''constructor''''s execution.
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|-
 
|-
 
|  01:04
 
|  01:04
 
| It can initialize''' instance member variables '''of the class.
 
| It can initialize''' instance member variables '''of the class.
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|-
 
|-
 
|  01:08
 
|  01:08
 
| Any other execution like calculation could also be given in the block.
 
| Any other execution like calculation could also be given in the block.
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|-
 
|-
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|-
 
|-
 
|  01:28
 
|  01:28
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| I also have a created a '''class '''named '''A''' .
+
| I also have a created a '''class''' named '''A''' .
  
  
 
|-
 
|-
 
|  01:33
 
|  01:33
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| Now inside '''class''' '''A ''', I will first create a variable of type '''int'''.
+
| Now inside '''class''' '''A''', I will first create a variable of type '''int'''.
  
  
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|-
 
|-
 
|  01:46
 
|  01:46
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| Within curly brackets type '''System''' ''dot '''''out''' ''dot'' '''println''' within brackets and double quotes '''Non static''' '''block of an instance of Class A '''''semicolon''.
+
| Within curly brackets type '''System''' dot '''out''' dot '''println''' within brackets and double quotes '''Non static''' '''block of an instance of Class A ''' semicolon.
−
 
+
  
 
|-
 
|-
 
|  02:12
 
|  02:12
−
| Then type '''System '''''dot'' '''out''' ''dot '''''println''' within brackets and double quotes '''The value of a''' is ''plus '''''a '''''semicolon''.
+
| Then type '''System''' dot '''out''' dot '''println''' within brackets and double quotes '''The value of a''' is plus '''a''' semicolon.
  
  
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|  02:35
 
|  02:35
 
| So type '''public A''' ''opening and closing brackets'', open the ''curly brackets''  press '''Enter'''.
 
| So type '''public A''' ''opening and closing brackets'', open the ''curly brackets''  press '''Enter'''.
−
 
  
 
|-
 
|-
 
|  02:51
 
|  02:51
−
| Then type  '''System''' ''dot '''''out '''''dot'' '''println''' within brackets and double quotes '''Constructing object of type A''' semicolon.
+
| Then type  '''System''' dot '''out''' dot '''println''' within brackets and double quotes '''Constructing object of type A''' semicolon.
−
 
+
  
 
|-
 
|-
 
|  03:10
 
|  03:10
−
| Then type '''System''' ''dot'' '''out '''''dot '''''println''' within brackets and double quotes '''The value of a '''is ''plus'' '''a '''''semicolon''.
+
| Then type '''System''' dot '''out '''dot '''println''' within brackets and double quotes '''The value of a''' is ''plus'' '''a ''' semicolon.
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+
  
 
|-
 
|-
 
|  03:35
 
|  03:35
 
| Now save this file.
 
| Now save this file.
 +
 
|-
 
|-
 
|  03:44
 
|  03:44
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| Inside  '''class NonStaticTest''' in''' Eclipse '''let us create an '''object '''of the '''class A'''.
+
| Inside  '''class NonStaticTest''' in '''Eclipse''' let us create an '''object''' of the '''class A'''.
−
 
+
  
 
|-
 
|-
 
|  03:53
 
|  03:53
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| So type '''A''' ''space '''''a1''' ''equal to''''' new''' ''space'' '''A''' opening and closing brackets semicolon
+
| So type '''A''' space '''a1''' ''equal to'' ''' new''' space '''A''' opening and closing brackets semicolon
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+
  
 
|-
 
|-
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|-
 
|-
 
|  04:12
 
|  04:12
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|So type '''A''''' space'' '''a2''' ''equal to'' '''new '''''space'' '''A''' opening and closing brackets semicolon.
+
|So type '''A''' space '''a2''' ''equal to'' '''new ''' space '''A''' opening and closing brackets semicolon.
  
  
 
|-
 
|-
 
|  04:25
 
|  04:25
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|Now  Save and run the file. So press '''Ctrl &S''' and '''Ctrl &F11 '''keys
+
|Now  Save and run the file. So press '''Ctrl &S''' and '''Ctrl &F11''' keys
  
  
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| 04:35
 
| 04:35
 
| As we can see when the first''' object '''is created, the '''non-static block''' is executed.
 
| As we can see when the first''' object '''is created, the '''non-static block''' is executed.
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|-
 
|  04:45
 
|  04:45
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|  '''non-static block'''  of an''' instance  of class A '''  and the''' instance variable 'a' '''is initialized to '''0'''.
+
|  '''non-static block'''  of an '''instance  of class A'''  and the''' instance variable 'a' '''is initialized to '''0'''.
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+
  
 
|-
 
|-
 
|  04:53
 
|  04:53
 
| Only after that the '''constructor''' is executed. Constructing object of type A  
 
| Only after that the '''constructor''' is executed. Constructing object of type A  
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|-
 
|-
 
|  05:02
 
|  05:02
 
| And here the''' instance variable''' is again initialized to '''0'''.
 
| And here the''' instance variable''' is again initialized to '''0'''.
−
 
  
 
|-
 
|-
 
|  05:07
 
|  05:07
 
| Then again when the second '''object''' is created, the '''non-static block''' is executed.
 
| Then again when the second '''object''' is created, the '''non-static block''' is executed.
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|-
 
|-
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|  05:20
 
|  05:20
 
|  We can have multiple '''non-static blocks''' in a '''class'''.
 
|  We can have multiple '''non-static blocks''' in a '''class'''.
−
 
  
 
|-
 
|-
 
|  05:25
 
|  05:25
 
| In this case they execute in the sequence in which they appear in the '''class.'''
 
| In this case they execute in the sequence in which they appear in the '''class.'''
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|-
 
|-
 
|  05:30
 
|  05:30
 
| We can try that now.
 
| We can try that now.
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|-
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|  05:43
 
|  05:43
 
| So again type inside curly brackets.
 
| So again type inside curly brackets.
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|-
 
|-
 
|  05:47
 
|  05:47
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|  '''System''' ''dot '''''out''' ''dot'' '''println''' within brackets and double quotes '''Second''' '''Non static''' '''block of an instance of Class A '''''semicolon''.
+
|  '''System''' ''dot '''''out''' ''dot'' '''println''' within brackets and double quotes '''Second''' '''Non static''' '''block of an instance of Class A '''semicolon.
−
 
+
  
 
|-
 
|-
 
|  06:08
 
|  06:08
 
| Then type '''System '''''dot'' '''out''' ''dot '''''println''' within brackets and double quotes '''The value of a''' is ''plus '''''a '''''semicolon''.
 
| Then type '''System '''''dot'' '''out''' ''dot '''''println''' within brackets and double quotes '''The value of a''' is ''plus '''''a '''''semicolon''.
−
 
  
 
|-
 
|-
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|-
 
|-
 
|  06:48
 
|  06:48
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|   we   see that after the first block is executed, the second is executed.
+
| we see that after the first block is executed, the second is executed.
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+
  
 
|-
 
|-
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|  07:07
 
|  07:07
 
| Now  you might feel why do we need '''constructors.'''
 
| Now  you might feel why do we need '''constructors.'''
−
 
  
 
|-
 
|-
 
|  07:10
 
|  07:10
 
| The answer is we don't need the '''default constructor'''.
 
| The answer is we don't need the '''default constructor'''.
−
 
  
 
|-  
 
|-  
 
|  07:15
 
|  07:15
 
| But the '''non-static block''' cannot be '''parameterized'''.
 
| But the '''non-static block''' cannot be '''parameterized'''.
−
 
  
 
|-
 
|-
 
|  07:18
 
|  07:18
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| You cannot have''' objects''' taking values from out side.
+
| You cannot have '''objects''' taking values from out side.
−
 
+
  
 
|-
 
|-
 
|  07:22
 
|  07:22
−
| So '''non-static block '''is not a substitute for '''constructor.'''  
+
| So '''non-static block''' is not a substitute for '''constructor.'''  
  
 
|-
 
|-
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|  07:29
 
|  07:29
 
|  In this tutorial we learnt :
 
|  In this tutorial we learnt :
−
 
  
 
|-
 
|-
 
|  07:32
 
|  07:32
 
| About '''non-static block'''  and how to use this block.
 
| About '''non-static block'''  and how to use this block.
−
 
−
 
−
 
  
 
|-
 
|-
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| 07:36
 
| 07:36
 
|  create a '''class '''named '''B.'''
 
|  create a '''class '''named '''B.'''
 +
 
|-
 
|-
 
| 07:39
 
| 07:39
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|-
 
|-
 
| 07:44
 
| 07:44
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|  Create an '''object''' of '''class B''' in the '''class NonStaticTest '''already created'''.'''
+
|  Create an '''object''' of '''class B''' in the '''class NonStaticTest '''already created.
  
 
|-
 
|-
 
| 07:49
 
| 07:49
 
|  Check the output.
 
|  Check the output.
−
 
−
 
  
 
|-
 
|-

Revision as of 15:05, 23 September 2014

Time Narration
00:02 Welcome to the Spoken Tutorial on Non-static block in java.
00:06 In this tutorial we will learn
00:08 About non-static block
00:10 When a non-static block executed?
00:13 Simple example of non-static block
00:16 And Why we need constructors?
00:18 Here we are using
  • Ubuntu version 11.10
  • Java Development Environment jdk 1.6
  • And Eclipse IDE 3.7.0
00:26 To follow this tutorial you must know
00:29 How to create a constructor in Java using Eclipse
00:33 If not, for relevant tutorials please visit our website which is as shown,

(http://www.spoken-tutorial.org)

00:38 Now we will see what a non-static block is.
00:42 Any code written between two curly brackets is a non-static block.
00:46 We can see the syntax here.
00:51 When is a non-static block executed ?
00:54 A non-static block is executedfor each object that is created.
00:58 It executes before the constructor's execution.
01:04 It can initialize instance member variables of the class.
01:08 Any other execution like calculation could also be given in the block.
01:14 Now, let us switch to Eclipse and try to use a non-static block.
01:22 I have already opened a class named NonStaticTest in Eclipse.


01:28 I also have a created a class named A .


01:33 Now inside class A, I will first create a variable of type int.


01:38 So type int a semicolon, then press Enter


01:46 Within curly brackets type System dot out dot println within brackets and double quotes Non static block of an instance of Class A semicolon.
02:12 Then type System dot out dot println within brackets and double quotes The value of a is plus a semicolon.


02:32 Now we will declare a constructor.
02:35 So type public A opening and closing brackets, open the curly brackets press Enter.
02:51 Then type System dot out dot println within brackets and double quotes Constructing object of type A semicolon.
03:10 Then type System dot out dot println within brackets and double quotes The value of a is plus a semicolon.
03:35 Now save this file.
03:44 Inside class NonStaticTest in Eclipse let us create an object of the class A.
03:53 So type A space a1 equal to new space A opening and closing brackets semicolon
04:08 Next line we will create one more object of class A.
04:12 So type A space a2 equal to new space A opening and closing brackets semicolon.


04:25 Now Save and run the file. So press Ctrl &S and Ctrl &F11 keys


04:32 We get the output as follows:
04:35 As we can see when the first object is created, the non-static block is executed.
04:45 non-static block of an instance of class A and the instance variable 'a' is initialized to 0.
04:53 Only after that the constructor is executed. Constructing object of type A
05:02 And here the instance variable is again initialized to 0.
05:07 Then again when the second object is created, the non-static block is executed.
05:16 This process is repeated.
05:20 We can have multiple non-static blocks in a class.
05:25 In this case they execute in the sequence in which they appear in the class.
05:30 We can try that now.
05:34 Include one more block after the first one in class A.
05:43 So again type inside curly brackets.
05:47 System dot out dot println within brackets and double quotes Second Non static block of an instance of Class A semicolon.
06:08 Then type System dot out dot println within brackets and double quotes The value of a is plus a semicolon.
06:30 Now save this file ,press Ctrl & S key simultaneously then press Ctrl & F11 to run the program.
06:44 We get the output as follows.
06:48 we see that after the first block is executed, the second is executed.
06:58 Only then the constructor is executed.
07:07 Now you might feel why do we need constructors.
07:10 The answer is we don't need the default constructor.
07:15 But the non-static block cannot be parameterized.
07:18 You cannot have objects taking values from out side.
07:22 So non-static block is not a substitute for constructor.
07:27 So let us summarizes
07:29 In this tutorial we learnt :
07:32 About non-static block and how to use this block.
07:35 For self assessment,
07:36 create a class named B.
07:39 Create a non-static block and a constructor as shown in the tutorial.
07:44 Create an object of class B in the class NonStaticTest already created.
07:49 Check the output.
07:51 To know more about the Spoken Tutorial Project
07:53 Watch the video available at http://spoken-tutorial.org/What_is_a_Spoken_Tutorial
07:56 It summarizes the Spoken Tutorial project
08:00 If you do not have good bandwidth, you can download and watch it


08:03 The Spoken Tutorial Project Team
08:06 Conducts workshops using spoken tutorials
08:08 Gives certificates for those who pass an online test
08:12 For more details, please write to contact@spoken-tutorial.org


08:18 Spoken Tutorial Project is a part of the Talk to a Teacher project
08:22 It is supported by the National Mission on Education through ICT, MHRD, Government of India
08:28 More information on this Mission is available at


08:37 Thus we have come to the end of this tutorial.
08:40 This is Arya Ratish from IIT BOmbay signing off. Thanks for joining.


Contributors and Content Editors

Arya Ratish, Devisenan, Gaurav, PoojaMoolya, Sandhya.np14, Sneha

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