Difference between revisions of "Java/C2/Non-static-block/English-timed"
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| 01:38 | | 01:38 | ||
− | | So type '''int a''' semicolon, then press ''Enter''. | + | | So, type: '''int a''' semicolon, then press '''Enter'''. |
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| 01:46 | | 01:46 | ||
− | | Within curly brackets, type: '''System''' dot '''out''' dot '''println''' within brackets and double quotes '''Non static | + | | Within curly brackets, type: '''System''' dot '''out''' dot '''println''' within brackets and double quotes '''Non static block of an instance of Class A''' semicolon. |
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| 02:12 | | 02:12 | ||
− | | Then type '''System''' dot '''out''' dot '''println''' within brackets and double quotes '''The value of a''' | + | | 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 | + | | So, type: '''public A''' opening and closing brackets open the curly brackets press '''Enter'''. |
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| 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. |
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| 03:10 | | 03:10 | ||
− | | Then type '''System''' dot '''out '''dot '''println''' within brackets and double quotes '''The value of a' | + | | Then type: '''System''' dot '''out '''dot '''println''' within brackets and double quotes '''The value of a is''' plus '''a ''' semicolon. |
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| 03:53 | | 03:53 | ||
− | | So type '''A''' space '''a1 | + | | So, type: '''A''' space '''a1''' equal to ''' new''' space '''A''' opening and closing brackets semicolon. |
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| 04:08 | | 04:08 | ||
− | | Next line we will create one more object of class '''A'''. | + | | Next line, we will create one more object of class '''A'''. |
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| 04:12 | | 04:12 | ||
− | |So type '''A''' space '''a2 | + | |So, type: '''A''' space '''a2''' equal to '''new ''' space '''A''' opening and closing brackets semicolon. |
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| 04:25 | | 04:25 | ||
− | |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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| 04:53 | | 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'''. |
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| 05:34 | | 05:34 | ||
− | | Include one more block after the first one in class A. | + | | Include one more block after the first one in class '''A'''. |
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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 | ||
− | | '''System | + | | '''System''' dot '''out''' dot '''println''' within brackets and double quotes '''Second Non static block of an instance of Class A''' semicolon. |
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| 06:08 | | 06:08 | ||
− | | Then type '''System | + | | Then type: '''System ''' dot '''out''' dot '''println''' within brackets and double quotes '''The value of a is''' plus '''a ''' semicolon . |
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| 06:30 | | 06:30 | ||
− | | Now save this file ,press''' Ctrl & S | + | | Now save this file , press''' Ctrl & S''' key simultaneously then press ''' Ctrl & F11 ''' to '''run''' the program. |
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| 07:15 | | 07:15 | ||
− | | But the '''non-static block''' cannot be ''' | + | | But the '''non-static block''' cannot be '''parametrized'''. |
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| 07:27 | | 07:27 | ||
− | | So let us | + | | So, let us summarize. |
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| 07:29 | | 07:29 | ||
− | | In this tutorial we learnt | + | | In this tutorial we learnt |
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| 07:32 | | 07:32 | ||
− | | | + | | about '''non-static block''' and how to use this block. |
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Revision as of 15:37, 1 April 2015
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:
|
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. |
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 executed for 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 parametrized. |
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 summarize. |
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 [1] |
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
http://spoken-tutorial.org/NMEICT-Intro |
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