Difference between revisions of "Java/C2/Introduction-to-Array/English-timed"
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{| border = 1 | {| border = 1 | ||
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|'''Time''' | |'''Time''' | ||
+ | |'''Narration''' | ||
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| 00:02 | | 00:02 | ||
Line 13: | Line 9: | ||
|- | |- | ||
| 00:07 | | 00:07 | ||
− | | In this tutorial, you will learn how to ''' | + | | In this tutorial, you will learn how to create '''array'''s and access elements in '''array'''s. |
− | + | ||
− | + | ||
|- | |- | ||
| 00:14 | | 00:14 | ||
− | | For this tutorial we are using | + | | For this tutorial, we are using: |
− | + | '''Ubuntu 11.10''' | |
− | + | '''JDK 1.6''' and | |
− | + | '''Eclipse 3.7.0''' | |
− | + | ||
− | + | ||
− | + | ||
|- | |- | ||
| 00:25 | | 00:25 | ||
− | + | | For this tutorial, you should have knowledge of '''data types''' and '''for loop''' in Java. | |
− | + | ||
|- | |- | ||
| 00:32 | | 00:32 | ||
− | | If not, for relevant | + | | If not, for relevant tutorials, please visit our website which is as shown. |
|- | |- | ||
| 00:38 | | 00:38 | ||
− | | | + | | '''Array'''s are a collection of data. |
− | + | ||
|- | |- | ||
| 00:40 | | 00:40 | ||
− | | For example, a list of marks, a list of names, a list of temperatures, a list of rainfall | + | | For example, a list of marks, a list of names, a list of temperatures, a list of rainfall. |
− | + | ||
|- | |- | ||
| 00:47 | | 00:47 | ||
− | | Each item has an index based on its position. | + | | Each item has an index, based on its position. |
− | + | ||
|- | |- | ||
| 00:52 | | 00:52 | ||
− | | The index of the first element is 0. | + | | The index of the first element is '''0'''. |
− | + | ||
|- | |- | ||
| 00:55 | | 00:55 | ||
| The index of the second element is 1 and so on. | | The index of the second element is 1 and so on. | ||
− | |||
|- | |- | ||
| 00:59 | | 00:59 | ||
| Let us now see how to store this data. | | Let us now see how to store this data. | ||
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|- | |- | ||
Line 72: | Line 56: | ||
|- | |- | ||
| 01:06 | | 01:06 | ||
− | | A '''class''' named '''ArraysDemo '''has already been created. | + | | A '''class''' named '''ArraysDemo''' has already been created. |
− | + | ||
|- | |- | ||
| 01:11 | | 01:11 | ||
− | | Within the main method, let us add the rainfall data. | + | | Within the '''main method''', let us add the rainfall data. |
|- | |- | ||
| 01:16 | | 01:16 | ||
− | | So | + | | So, inside '''main function''', type: |
− | + | ||
|- | |- | ||
| 01:18 | | 01:18 | ||
− | | '''int rainfall | + | | '''int rainfall''' open and close square brackets equal to within curly brackets type '''25, 31, 29, 13, 27, 35, 12''' and finally the semicolon. |
− | + | ||
|- | |- | ||
| 01:53 | | 01:53 | ||
− | | Note the square braces after the '''variable '''name''' rainfall'''. | + | | Note that the square braces after the '''variable''' name '''rainfall'''. |
− | + | ||
|- | |- | ||
| 01:58 | | 01:58 | ||
− | | This declares '''rainfall''' as an '''array''' of | + | | This declares '''rainfall''' as an '''array''' of integers. |
− | + | ||
|- | |- | ||
| 02:03 | | 02:03 | ||
− | | The braces are used to specify the elements of the array. | + | | The braces are used to specify the elements of the '''array'''. |
|- | |- | ||
| 02:09 | | 02:09 | ||
− | | | + | | Let us now access data. |
|- | |- | ||
| 02:12 | | 02:12 | ||
− | | So on the | + | | So on the next line, type: |
− | + | ||
|- | |- | ||
| 02:14 | | 02:14 | ||
− | | '''System | + | | '''System ''' dot '''out ''' dot '''println''' '''rainfall''' in square brackets type '''2'''. |
− | + | ||
|- | |- | ||
| 02:28 | | 02:28 | ||
− | | We are printing the element with | + | | We are printing the element with the index number 2. |
− | + | ||
|- | |- | ||
| 02:32 | | 02:32 | ||
− | | In other words, the third element in the array i.e.29. | + | | In other words, the third element in the '''array''' i.e. 29. |
− | + | ||
|- | |- | ||
| 02:38 | | 02:38 | ||
− | | Let us save | + | | Let us '''save''' and '''run''' the program. |
|- | |- | ||
| 02:43 | | 02:43 | ||
− | |As we can see, the output is the third element,i.e '''29'''. | + | |As we can see, the output is the third element, i.e '''29'''. |
− | + | ||
|- | |- | ||
| 02:49 | | 02:49 | ||
− | | Now let us type | + | | Now, let us type 0 in place of 2. |
|- | |- | ||
| 02:56 | | 02:56 | ||
− | | | + | | '''Save''' and '''run''' the program. |
|- | |- | ||
| 03:00 | | 03:00 | ||
− | | As we can see, the output is the first value | + | | As we can see, the output is the first value i.e 25. |
− | + | ||
|- | |- | ||
| 03:07 | | 03:07 | ||
− | | Now let us modify the value of the first item | + | | Now, let us modify the value of the first item. |
|- | |- | ||
| 03:13 | | 03:13 | ||
− | | | + | | So, type: '''rainfall[0] = 11;''' |
− | + | ||
|- | |- | ||
| 03:27 | | 03:27 | ||
− | | Now let us see its value. So save and run the program | + | | Now, let us see its value. So '''save''' and '''run''' the program. |
− | + | ||
|- | |- | ||
Line 169: | Line 140: | ||
|- | |- | ||
| 03:40 | | 03:40 | ||
− | | Now what if we know | + | | Now, what if we know only the size of the '''array''' and do not know the values. |
|- | |- | ||
| 03:45 | | 03:45 | ||
− | | Let us see how to create such array. | + | | Let us see how to create such '''array'''. |
|- | |- | ||
| 03:49 | | 03:49 | ||
− | | Remove everything in main function and type | + | | Remove everything in '''main''' function and type: |
|- | |- | ||
| 03:57 | | 03:57 | ||
− | | '''int squares [] = | + | | '''int squares[] = new int[10];''' |
|- | |- | ||
| 04:19 | | 04:19 | ||
− | | This statement creates an array of integers having 10 elements. The name of the array is '''squares'''. | + | | This statement creates an '''array''' of integers having 10 elements. The name of the '''array''' is '''squares'''. |
|- | |- | ||
| 04:30 | | 04:30 | ||
− | | Now let us add some values to it | + | | Now, let us add some values to it. |
|- | |- | ||
| 04:33 | | 04:33 | ||
− | | So | + | | So, type: |
− | + | ||
|- | |- | ||
Line 198: | Line 168: | ||
|- | |- | ||
| 04:43 | | 04:43 | ||
− | | Next line'''squares[1] = 4;''' | + | | Next line, '''squares[1] = 4;''' |
|- | |- | ||
| 04:53 | | 04:53 | ||
− | | Next line'''squares[2] = 9;''' | + | | Next line, '''squares[2] = 9;''' |
|- | |- | ||
| 05:04 | | 05:04 | ||
| '''squares[3] = 16;''' | | '''squares[3] = 16;''' | ||
− | |||
|- | |- | ||
| 05:15 | | 05:15 | ||
− | | So | + | | So, we have entered the squares of first four numbers. |
|- | |- | ||
| 05:20 | | 05:20 | ||
− | | Now what about the other elements of the array. Let us see what they contain. | + | | Now what about the other elements of the '''array'''. Let us see what they contain. |
|- | |- | ||
| 05:26 | | 05:26 | ||
− | | So | + | | So, we shall print the sixth value in the '''array'''. |
− | + | ||
|- | |- | ||
| 05:30 | | 05:30 | ||
− | | Type '''System.out.println(squares [5]); ''' | + | | Type: '''System''' S capital '''.out.println(squares[5]);''' |
− | + | ||
− | + | ||
− | + | ||
|- | |- | ||
| 05:56 | | 05:56 | ||
− | | Save and run the program.We see that the value is zero. | + | | '''Save''' and '''run''' the program. We see that the value is zero. |
|- | |- | ||
| 06:05 | | 06:05 | ||
− | + | | This is because when we create an '''array''' of integers, all the values are initialized to 0. | |
|- | |- | ||
| 06:11 | | 06:11 | ||
− | | Similarly an array of floats will have all its values initialized to 0.0. | + | | Similarly, an '''array''' of floats will have all its values initialized to 0.0. |
− | + | ||
|- | |- | ||
| 06:18 | | 06:18 | ||
− | | It would be a long process if we have to type each value into the array. Instead, let us use a for loop. | + | | It would be a long process if we have to type each value into the '''array'''. Instead, let us use a for loop. |
|- | |- | ||
| 06:28 | | 06:28 | ||
− | | So | + | | So, type: |
− | + | '''int n, x ;''' | |
− | + | ||
− | '''int n, x ; | + | |
− | + | ||
'''for(x = 4; x < 10; x = x + 1){''' | '''for(x = 4; x < 10; x = x + 1){''' | ||
'''n = x + 1;''' | '''n = x + 1;''' | ||
− | '''squares [x] = n * n; | + | '''squares[x] = n * n;''' |
− | + | ||
− | + | ||
+ | '''}''' | ||
|- | |- | ||
| 07:25 | | 07:25 | ||
− | |So | + | |So, we iterate over numbers from 4 to 9 and set the corresponding element in the '''array'''. |
− | + | ||
|- | |- | ||
| 07:36 | | 07:36 | ||
− | | Now let us see the output. | + | | Now, let us see the output. |
|- | |- | ||
| 07:38 | | 07:38 | ||
− | + | | As we can see, we are printing the value of sixth element in '''array'''. So, '''Save''' and '''run'''. | |
|- | |- | ||
| 07:52 | | 07:52 | ||
− | | We | + | | We see the sixth element is now square of 6 which is 36. |
− | + | ||
|- | |- | ||
| 07:57 | | 07:57 | ||
− | | In fact now we can set all the values inside the for loop. | + | | In fact, now we can set all the values inside the '''for loop'''. |
|- | |- | ||
| 08:03 | | 08:03 | ||
− | | | + | | Remove the lines that set the values manually and change '''4''' to '''0'''. |
− | + | ||
|- | |- | ||
| 08:14 | | 08:14 | ||
− | | This way all the elements from index 0 to | + | | This way, all the elements from index 0 to 9 are set to the corresponding squares. |
− | + | ||
|- | |- | ||
| 08:21 | | 08:21 | ||
| We shall now see the value of the third element. | | We shall now see the value of the third element. | ||
− | |||
|- | |- | ||
| 08:25 | | 08:25 | ||
− | | So change '''5 '''to '''2''' | + | | So, change '''5''' to '''2'''. |
− | + | ||
|- | |- | ||
| 08:30 | | 08:30 | ||
− | | Save and run | + | | '''Save''' and '''run'''. |
− | + | ||
|- | |- | ||
| 08:35 | | 08:35 | ||
− | | As we can see, the value of the third element has been set in the loop and it is 9. | + | | As we can see, the value of the third element has been set in the '''loop''' and it is 9. |
|- | |- | ||
| 08:42 | | 08:42 | ||
− | | This way, | + | | This way, '''array'''s can be created and used. |
|- | |- | ||
Line 321: | Line 275: | ||
|- | |- | ||
| 08:53 | | 08:53 | ||
− | | In this tutorial we have learnt | + | | In this tutorial, we have learnt: |
|- | |- | ||
| 08:55 | | 08:55 | ||
− | | | + | |To declare and initialize an '''array'''. |
|- | |- | ||
| 08:58 | | 08:58 | ||
− | | And access element in an array | + | |And access an element in an '''array'''. |
|- | |- | ||
| 09:01 | | 09:01 | ||
− | | | + | | The assignment for this tutorial is: |
− | + | ||
|- | |- | ||
| 09:04 | | 09:04 | ||
− | | Given an array of integers, find the sum of all the elements in the array. | + | | Given an '''array''' of integers, find the sum of all the elements in the '''array'''. |
|- | |- | ||
| 09:10 | | 09:10 | ||
− | | To know more about the | + | | To know more about the Spoken Tutorial project, |
|- | |- | ||
| 09:13 | | 09:13 | ||
Line 345: | Line 298: | ||
|- | |- | ||
| 09:19 | | 09:19 | ||
− | | It | + | | It summarizes the project. If you do not have good bandwidth, you can download and watch it. |
|- | |- | ||
| 09:26 | | 09:26 | ||
− | | The Spoken Tutorial | + | | The Spoken Tutorial project team: Conducts workshops using spoken tutorials and gives certificates to those who pass an online test. |
|- | |- | ||
| 09:34 | | 09:34 | ||
Line 356: | Line 309: | ||
|- | |- | ||
| 09:40 | | 09:40 | ||
− | | | + | | Spoken Tutorial project is a part of the Talk to a Teacher project. |
|- | |- | ||
| 09:44 | | 09:44 | ||
− | | It is supported by the | + | | It is supported by the National Mission on Education through ICT, MHRD, Government of India. |
|- | |- | ||
| 09:50 | | 09:50 | ||
− | | | + | | More information on this mission is available at '''spoken HYPHEN tutorial DOT org SLASH NMEICT HYPHEN Intro'''. |
|- | |- | ||
| 09:57 | | 09:57 | ||
| This script has been contributed by '''TalentSprint'''. | | This script has been contributed by '''TalentSprint'''. | ||
− | + | This is Prathamesh Salunke, signing off. Thanks for joining. | |
− | This is Prathamesh Salunke signing off. Thanks for joining. | + | |
− | + | ||
− | + | ||
− | + | ||
|} | |} |
Latest revision as of 19:29, 20 February 2017
Time | Narration |
00:02 | Welcome to the spoken tutorial on Introduction to Arrays. |
00:07 | In this tutorial, you will learn how to create arrays and access elements in arrays. |
00:14 | For this tutorial, we are using:
Ubuntu 11.10 JDK 1.6 and Eclipse 3.7.0 |
00:25 | For this tutorial, you should have knowledge of data types and for loop in Java. |
00:32 | If not, for relevant tutorials, please visit our website which is as shown. |
00:38 | Arrays are a collection of data. |
00:40 | For example, a list of marks, a list of names, a list of temperatures, a list of rainfall. |
00:47 | Each item has an index, based on its position. |
00:52 | The index of the first element is 0. |
00:55 | The index of the second element is 1 and so on. |
00:59 | Let us now see how to store this data. |
01:03 | So switch to Eclipse. |
01:06 | A class named ArraysDemo has already been created. |
01:11 | Within the main method, let us add the rainfall data. |
01:16 | So, inside main function, type: |
01:18 | int rainfall open and close square brackets equal to within curly brackets type 25, 31, 29, 13, 27, 35, 12 and finally the semicolon. |
01:53 | Note that the square braces after the variable name rainfall. |
01:58 | This declares rainfall as an array of integers. |
02:03 | The braces are used to specify the elements of the array. |
02:09 | Let us now access data. |
02:12 | So on the next line, type: |
02:14 | System dot out dot println rainfall in square brackets type 2. |
02:28 | We are printing the element with the index number 2. |
02:32 | In other words, the third element in the array i.e. 29. |
02:38 | Let us save and run the program. |
02:43 | As we can see, the output is the third element, i.e 29. |
02:49 | Now, let us type 0 in place of 2. |
02:56 | Save and run the program. |
03:00 | As we can see, the output is the first value i.e 25. |
03:07 | Now, let us modify the value of the first item. |
03:13 | So, type: rainfall[0] = 11; |
03:27 | Now, let us see its value. So save and run the program. |
03:34 | As we can see, the value has been changed to 11. |
03:40 | Now, what if we know only the size of the array and do not know the values. |
03:45 | Let us see how to create such array. |
03:49 | Remove everything in main function and type: |
03:57 | int squares[] = new int[10]; |
04:19 | This statement creates an array of integers having 10 elements. The name of the array is squares. |
04:30 | Now, let us add some values to it. |
04:33 | So, type: |
04:35 | squares[0] = 1; |
04:43 | Next line, squares[1] = 4; |
04:53 | Next line, squares[2] = 9; |
05:04 | squares[3] = 16; |
05:15 | So, we have entered the squares of first four numbers. |
05:20 | Now what about the other elements of the array. Let us see what they contain. |
05:26 | So, we shall print the sixth value in the array. |
05:30 | Type: System S capital .out.println(squares[5]); |
05:56 | Save and run the program. We see that the value is zero. |
06:05 | This is because when we create an array of integers, all the values are initialized to 0. |
06:11 | Similarly, an array of floats will have all its values initialized to 0.0. |
06:18 | It would be a long process if we have to type each value into the array. Instead, let us use a for loop. |
06:28 | So, type:
int n, x ; for(x = 4; x < 10; x = x + 1){ n = x + 1; squares[x] = n * n; } |
07:25 | So, we iterate over numbers from 4 to 9 and set the corresponding element in the array. |
07:36 | Now, let us see the output. |
07:38 | As we can see, we are printing the value of sixth element in array. So, Save and run. |
07:52 | We see the sixth element is now square of 6 which is 36. |
07:57 | In fact, now we can set all the values inside the for loop. |
08:03 | Remove the lines that set the values manually and change 4 to 0. |
08:14 | This way, all the elements from index 0 to 9 are set to the corresponding squares. |
08:21 | We shall now see the value of the third element. |
08:25 | So, change 5 to 2. |
08:30 | Save and run. |
08:35 | As we can see, the value of the third element has been set in the loop and it is 9. |
08:42 | This way, arrays can be created and used. |
08:50 | We have come to the end of this tutorial. |
08:53 | In this tutorial, we have learnt: |
08:55 | To declare and initialize an array. |
08:58 | And access an element in an array. |
09:01 | The assignment for this tutorial is: |
09:04 | Given an array of integers, find the sum of all the elements in the array. |
09:10 | To know more about the Spoken Tutorial project, |
09:13 | watch the video available at the following link. |
09:19 | It summarizes the project. If you do not have good bandwidth, you can download and watch it. |
09:26 | The Spoken Tutorial project team: Conducts workshops using spoken tutorials and gives certificates to those who pass an online test. |
09:34 | For more details, please write to contact AT spoken HYPHEN tutorial DOT org. |
09:40 | Spoken Tutorial project is a part of the Talk to a Teacher project. |
09:44 | It is supported by the National Mission on Education through ICT, MHRD, Government of India. |
09:50 | More information on this mission is available at spoken HYPHEN tutorial DOT org SLASH NMEICT HYPHEN Intro. |
09:57 | This script has been contributed by TalentSprint.
This is Prathamesh Salunke, signing off. Thanks for joining. |