Difference between revisions of "Java/C2/Methods/English-timed"
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Revision as of 12:26, 1 January 2014
| Time' | Narration
|
| 00:02 | Welcome to the Spoken Tutorial on methods in java. |
| 00:06 | In this tutorial we will learn |
| 00:08 | To create a method. |
| 00:10 | And To call a method. |
| 00:13 | Here we are using |
| 00:14 | Ubuntu version 11.10 |
| 00:17 | Java Development kit 1.6 and |
| 00:20 | Eclipse 3.7.0
|
| 00:24 | To follow this tutorial you must know how to write, compile and run a simple java program in eclipse.
|
| 00:32 | If not, for relevant tutorials please visit our website which is as shown, |
| 00:40
|
A java method is a collection of statements that performs a specified operation. |
| 00:46 | Let us now write a method.
|
| 00:50 | So, in the eclipse, I have already created a project Methods. |
| 00:57 | In the project, I have created a java class name MethodDemo. |
| 01:06 | In the class outside the main method we will write a method.
|
| 01:13 | So type void name of the method |
| 01:19 | Let us name it as displayMessage parentheses Enter |
| 01:29 | And curly brackets. |
| 01:32 | A method can return a value. |
| 01:34 | But if you don’t want the method to return a value then the keyword voidis used. |
| 01:42 | Alright now inside the curly brackets, let us print a message. |
| 01:47 | So type System dot out dot println Hello Method. |
| 02:06 | So we have written a method. |
| 02:10 | Now we will call this method. |
| 02:13 | So inside the Main method, we will create an object of the classMethodDemo. |
| 02:21 | So MethodDemo object name. |
| 02:26 | Let's name it as md =new MethodDemo parentheses, semicolon. |
| 02:37 | So we have created an object mdof the class MethodDemo using the New operator. |
| 02:48 | Now let us call the method displayMessage. |
| 02:51 | So type md dot displayMessage
|
| 03:00 | The Dot operator is used to call the method. |
| 03:06 | Now let us Run this application by clicking on Runicon. |
| 03:14 | We see the output Hello Method on the console |
| 03:20 | Now let us return an integer instead ofvoid. |
| 03:26 | So type int. |
| 03:32 | Also make the method public, that is accessible everywhere. |
| 03:37 | By default it is private, that is accessible only within the class where it is written.
|
| 03:45 | Now inside the method type return seven, semicolon. |
| 03:55 | Remember that we write the return statement at the end of all in the method. |
| 04:02 | This is because after return statement no other statements are executed. |
| 04:08 | Now inside the Main method at the end type the print statement. |
| 04:15 | So type System dot out dot println(); |
| 04:23 | Within parenthesis we will call the method. |
| 04:28 | So put md dot method inside the parentheses remove the semi-colon. |
| 04:37 | This will print the return value of the method. |
| 04:42 | Run the application. |
| 04:45 | We see in the output, the value 7 is printed. |
| 04:51 | Now we will write another method and call this methd in displayMessage. |
| 04:59 | So type public void method name square within parentheses int a. |
| 05:15 | Here we are giving int a as a parameter to our method. |
| 05:20 | Now within curly brackets type, System dot out dot println within parentheses a into a. |
| 05:37 | So we have written a square method. |
| 05:40 | That will display a square of an integer which is given as a parameter. |
| 05:48 | Let us call this method in the displayMessage method. |
| 05:53 | So type square within parentheses an integer 5, semicolon. |
| 06:07 | Run this application. |
| 06:12 | We see that the output displays the square of 5 that is 25. |
| 06:19 | Now let us understand the flow of the application. |
| 06:24 | The starting point is the Main method. |
| 06:29 | In the Main method, we have first called the displayMessage. |
| 06:34 | So the control goes to the displayMessage. |
| 06:40 | And all the statements in the displayMessage are executed. |
| 06:45 | The first one is the print statement. |
| 06:50 | Then it comes across the square method. |
| 06:54 | So the control jumps to the square method. |
| 06:57 | The square method takes an integer 5 and returns the square of the integer i.e. 25. |
| 07:06 | Then the control goes back to the displayMessage. |
| 07:10 | And it returns the value 7. |
| 07:14 | Then the control jumps back to the Main function. |
| 07:20 | Since there are no statements left to execute, in the main method the application terminates |
| 07:29 | Alright now let us make displayMessage as static. |
| 07:35 | So after public type static. |
| 07:40 | We see that we cannot call a non static method inside the static method |
| 07:47 | So we will comment this call. |
| 07:52 | Since Main is a static method, we can call the static displayMessage inside this |
| 08:02 | Now for static method we do not need to create an object. |
| 08:07 | So we will comment this object creation. |
| 08:11 | Also we will Delete md. |
| 08:18 | Run the application. |
| 08:22 | We see the output Hello Method and 7. |
| 08:27 | We do not see 25 because we have commented the call to square method |
| 08:34 | We can also call method from other class. |
| 08:38 | For that I have created a class Demo. |
| 08:45 | Inside the class create a method. |
| 08:48 | So type public void show parentheses Enter |
| 08:56 | Inside curly brackets, System dot out dot println |
| 09:07 | I am from other class.
|
| 09:13 | Save the file. |
| 09:16 | Go back to method MethodDemo class |
| 09:19 | Now we will call this show method inside the method MethodDemo class. |
| 09:28 | For that we need to create the object of the class Demo. |
| 09:22 | This is because the show method belongs to the class Demo. |
| 09:38 | So type Demo d=new Demo parentheses, semicolon |
| 09:48 | Then call the method show parentheses. |
| 09:54 | Lets Run this application. |
| 09:58 | We see on the console I am from other class. |
| 10:04 | This is how methods are used in java. |
| 10:09 | The method name and the parameters forms the signature of the method. |
| 10:14 | While the curly brackets and the statements forms the body of the method. |
| 10:23 | So in this tutorial, we have learnt |
| 10:25 | To create a method |
| 10:27 | To call a method |
| 10:29 | And Different signatures of methods
|
| 10:32 | For self assessment, create a method which prints the cube of an integer. |
| 10:38 | To know more about the Spoken Tutorial Project |
| 10:41 | Watch the video available at http://spoken-tutorial.org/What_is_a_Spoken_Tutorial |
| 10:47 | It summarizes the Spoken Tutorial project |
| 10:50 | If you do not have good bandwidth, you can download and watch it
|
| 10:54 | The Spoken Tutorial Project Team |
| 10:56 | Conducts workshops using spoken tutorials |
| 10:58 | Gives certificates to those who have pass an online test |
| 11:02 | For more details, please write to contact@spoken-tutorial.org
|
| 11:08 | Spoken Tutorial Project is a part of the Talk to a Teacher project |
| 11:12 | It is supported by the National Mission on Education through ICT, MHRD, Government of India |
| 11:18 | More information on this Mission is available at
http://spoken-tutorial.org/NMEICT-Intro
|
| 11:27 | We have come to the end of this tutorial. |
| 11:29 | Thanks for joining. |
| 11:30 | This is Prathamesh Salunke signing off.
Jai Hind. |
Contributors and Content Editors
Arya Ratish, Gaurav, Jyotisolanki, PoojaMoolya, Priyacst, Sandhya.np14, Sneha
