Difference between revisions of "Java/C2/Methods/English-timed"
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| − | | To know more about the Spoken Tutorial | + | | To know more about the Spoken Tutorial project, |
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|10:41 | |10:41 | ||
| − | | | + | | watch the video available at [http://spoken-tutorial.org/What_is_a_Spoken_Tutorial] |
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Revision as of 11:49, 31 March 2015
| 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 void is 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 class MethodDemo. |
| 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 md of 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 Run icon. |
| 03:14 | We see the output Hello Method on the console. |
| 03:20 | Now, let us return an integer instead of void. |
| 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 statements 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 parentheses, we will call the method. |
| 04:28 | So, put md dot method inside the parentheses, remove the semicolon. |
| 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 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. |
| 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 form the signature of the method |
| 10:14 | while the curly brackets and the statements form 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 [1] |
| 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 passed 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 |
| 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
