Java/C2/Array-Operations/English-timed

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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


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


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();


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.


07:15 Let'sChange 5 to 3.


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


07:44 Save and Run the program


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


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]
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10:05 If you do not have good bandwidth, you can download and watch it
10:09 The Spoken Tutorial Project Team.
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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.


Contributors and Content Editors

Gaurav, Krupali, PoojaMoolya, Sandhya.np14, Sneha