Difference between revisions of "Java/C2/Array-Operations/English-timed"

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|* '''import''' the '''class''' '''Arrays ''' and  
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|* perform basic operations on '''arrays'''.
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|* How to '''import''' the '''class''' '''Arrays'''.
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|* Perform array operations like  '''toStrings''', '''sort''', '''copy''', '''fill'''.
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|Perform array operations like  '''toStrings''', '''sort''', '''copy''', '''fill'''.
  
 
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|  The Spoken Tutorial project team:
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Latest revision as of 15:16, 28 March 2017

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 of arrays in Java.
00:30 If not, for relevant tutorials, please visit our website which is as shown. [1]
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 curly 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 So, type: String mStr equal to Arrays dot toString parentheses inside parentheses will give the array name i.e. marks.
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 parentheses 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 parentheses 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 elements 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 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 array i.e marks;
05:05 This is our first argument and second is the value that should be filled 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);
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, over here we will copy 5.
06:47 Then, in arrays dot toString, change marks to marksCopy.
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's Change 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 method 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 behavior ensures that continuity of ranges is maintained.
09:07 (0, 4) implies from index 0 to 3.
09:12 (4, 6) will imply index from 4 to 5.
09:17 So it behaves as if (0, 4) + (4, 6) = (0, 5).
09:26 This brings us to 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 toStrings, sort, copy, fill.
09:44 For assignment:
09:46 Read about the Arrays.equals method and find out what it does.
09:53 To know more about the Spoken Tutorial project,
09:55 watch the video available at [2].
10:02 It summarizes the Spoken Tutorial project.
10:05 If you do not have good bandwidth, you can download and watch it.
10:09 The Spoken Tutorial project team: Conducts workshops using Spoken Tutorials, gives certificates to those who pass an online test.
10:16 For more details, please write to contact @ spoken HYPHEN tutorial DOT org.
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

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