Java/C2/Array-Operations/English-timed
From Script | Spoken-Tutorial
| Time | Narration |
| 00:02 | Welcome to the spoken tutorial on Array Operations in java. |
| 00:07 | In this tutorial, you will learn how to |
| 00:09 | import the class Arrays and, |
| 00:12 | perform basic operations on arrays. |
| 00:15 | 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 on arrays in Java.
|
| 00:30 | If not, for relevant tutorial please visit our website which is as shown http://spoken-tutorial.org |
| 00:35 | The methods for array operations are available in a class called Arrays.
|
| 00:40 | To access them, we need to import that class.
|
| 00:43 | It is done by the statement import java.util.Arrays semicolon
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| 00:50 | We can access a method from the class.
|
| 00:52 | We do it by adding a dot and the method name.
|
| 00:56 | So Arrays dot toString means toString method from the Arrays class. |
| 01:05 | Now Switch to eclipse.
|
| 01:08 | We have already created a class ArraysDemo.
|
| 01:13 | Let us now import the class Arrays. |
| 01:16 | The import statement is written before the class definition.
|
| 01:22 | So Before public class, type
|
| 01:26 | import java.util.Arrays semicolon
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| 01:46 | This statement says that java contains a package called util which contains the class Arrays and it has to be imported. |
| 01:59 | Now let us add an array.
|
| 02:01 | Inside the main function,type
|
| 02:03 | int marks open and close square brackets equal to within brackets 2, 7, 5, 4, 8 |
| 02:20 | Now we shall use a method available in the Arrays class to get a string representation of the array and print it.
|
| 02:28 | SoType String mStr equal to Arrays dot toString Paranthesis inside Paranthesis will give the array name i.emarks |
| 02:50 | Now this toString method will give the string representation of the array.
|
| 02:56 | we shall print the marks.
|
| 02:58 | So, type System dot out dot println 'inside Paranthesis type mStr
|
| 03:12 | Now let us look at the output so save and run the program |
| 03:18 | As we can see in the output, the toString method has given a string representation of the array.
|
| 03:26 | Now let us look at sorting the elements of the array. |
| 03:31 | So before the line Arrays dot toString type Arrays dot sort within parenthesis the Array name i.e marks
|
| 03:46 | So the sort method in the Arrays class, sorts the elements of the array passed to it.
|
| 03:53 | Now we are sorting the element of the array marks and then printing the string form of it.
|
| 04:04 | Let us look at the output.So save and run |
| 04:11 | As we can see in the output the sort method has sorted to the array in the ascending order
|
| 04:19 | Note that the sort method has changed the array itself.
|
| 04:22 | This type of sorting is called inplace sorting.
|
| 04:26 | It means that the array which contains the elements is changed as a result of sorting.
|
| 04:33 | The next method we are going to look at, is fill |
| 04:38 | The fill method takes two arguments.
|
| 04:43 | Remove the sorting line and
|
| 04:50 | Type Arrays dot fill within brackets the name of the arrays i.e marks; |
| 05:05 | This is our first argument and second is the value that should be felt in the array we will give it 6 and semicolon. Save and Run |
| 05:24 | As we can see, as the name goes, the fill method fills the array with the given argument i.e 6
|
| 05:32 | The next method we are going to look at, is copyOf |
| 05:37 | We are going to copy all the elements of the array marks into the array marksCopy |
| 05:44 | So remove arrays dot fill |
| 05:48 | And Type int marksCopy []; |
| 05:59 | next line, Type marksCopy = arrays. copyOf(marks, 5);
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| 06:25 | This method takes two arguments.
|
| 06:29 | The first argument is the name of the array from which you want to copy the elements.i.e marks |
| 06:39 | the second is the no.of elements to copy overhere we will copy 5. |
| 06:47 | Then in arrays dot tostring change marks to marks copy
|
| 06:55 | Now save and run the program |
| 07:01 | We see that the elements of the array marks have been copied to the array marksCopy. |
| 07:10 | Let us see what happens if we change the no.of elements to be copied.
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| 07:15 | Let'sChange 5 to 3.
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| 07:19 | Save and Run |
| 07:24 | As we can see, only the first three elements have been copied.
|
| 07:31 | Let us see what happens if the no.of elements to be copied is greater than the total no.of elements in the array. |
| 07:39 | So Change 3 to 8
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| 07:44 | Save and Run the program
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| 07:48 | As we can see, the extra elements have been set to the default value, which is 0.
|
| 07:54 | Next we'll see how to copy a range of values. |
| 07:58 | So Change copyOf to copyOfRange and 8 to 1, 4 |
| 08:15 | This methods copies all the elements starting from the index 1 and stopping at index 3.
|
| 08:27 | Save and Run |
| 08:31 | As we can see, the elements from index 1 to 3 have been copied.
|
| 08:39 | Note that we have given 1, 4 as our arguments
|
| 08:47 | But even, then the element at index 4 has not been copied.
|
| 08:50 | Only the elements till index 3 have been copied. It stops one index before the given range |
| 09:01 | So This behaviour ensures that continuity of ranges is maintained.
|
| 09:07 | (0, 4) implies from index 0 to index 3 |
| 09:12 | (4, 6) will implies index from 4 to 5
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| 09:17 | So it behaves as if (0, 4) + (4, 6) = (0, 5) |
| 09:26 | This brings us o the end of this tutorial. |
| 09:31 | In this tutorial we have learnt |
| 09:33 | how to import the class Arrays. |
| 09:36 | Perform array operations like to strings,sort, copy, fill. |
| 09:44 | For assignment |
| 09:46 | Read about the Arrays.equals method and find out what is does. |
| 09:53 | To know more about the Spoken Tutorial project, |
| 09:55 | Watch the video available at[1] |
| 10:02 | It summarises the Spoken Tutorial project |
| 10:05 | If you do not have good bandwidth, you can download and watch it |
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| 10:22 | Spoken Tutorial Project is a part of the Talk to a Teacher project and is supported by the National Mission on Education through ICT, MHRD, Government of India. |
| 10:31 | More information on this Mission is available at spoken HYPHEN tutorial DOT org SLASH NMEICT HYPHEN Intro |
| 10:39 | This tutorial has been contributed by TalentSprint. Thanks for joining. |
| 10:43 | This is Prathmesh Salunke Signing off. Jai Hind.
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