Difference between revisions of "Java/C2/Errors-and-Debugging-in-Eclipse/English-timed"
From Script | Spoken-Tutorial
Sandhya.np14 (Talk | contribs) |
PoojaMoolya (Talk | contribs) |
||
| (One intermediate revision by one other user not shown) | |||
| Line 20: | Line 20: | ||
|- | |- | ||
| 00:20 | | 00:20 | ||
| − | | For this tutorial, we are using | + | | For this tutorial, we are using '''Ubuntu 11.10''' and '''Eclipse 3.7'''. |
| − | + | ||
| − | '''Ubuntu 11.10''' and | + | |
| − | + | ||
| − | '''Eclipse 3.7'''. | + | |
|- | |- | ||
| Line 44: | Line 40: | ||
|- | |- | ||
| 00:45 | | 00:45 | ||
| − | | | + | | Missing semicolon(;) |
|- | |- | ||
| 00:47 | | 00:47 | ||
| − | | | + | | Missing double quotes(" ") around the message |
|- | |- | ||
| 00:50 | | 00:50 | ||
| − | | | + | | Mis-match of 'file name' and 'class name' and |
|- | |- | ||
| 00:52 | | 00:52 | ||
| − | | | + | | Typing the print statement in lower-case. |
|- | |- | ||
| Line 61: | Line 57: | ||
|- | |- | ||
| 01:04 | | 01:04 | ||
| − | | | + | | Here we have the '''Eclipse IDE''' and the project used for the ''' HelloWorld''' tutorial. |
|- | |- | ||
| Line 81: | Line 77: | ||
|- | |- | ||
| 02:44 | | 02:44 | ||
| − | | | + | | The list of errors is displayed by hovering the mouse over the cross mark. |
|- | |- | ||
| 02:51 | | 02:51 | ||
| − | | | + | |The first error displayed is: '''syntax error, insert semi-colon to complete block statements'''. |
|- | |- | ||
| Line 113: | Line 109: | ||
|- | |- | ||
| 03:41 | | 03:41 | ||
| − | | Let us add double quotes before and after the message. | + | | Let us add ''double quotes'' before and after the message. |
|- | |- | ||
| 03:55 | | 03:55 | ||
| − | |''' Ctrl s''' to '''Save'''. We see that the red cross mark is gone and the program is error free. So, let us '''run''' the program and see what happens. | + | |''' Ctrl s''' to '''Save'''. We see that the red-cross mark is gone and the program is error free. So, let us '''run''' the program and see what happens. |
|- | |- | ||
| 04:10 | | 04:10 | ||
| − | | '''Run as''' > '''Java | + | | '''Run as''' > '''Java application''' |
|- | |- | ||
| Line 133: | Line 129: | ||
|- | |- | ||
| 04:25 | | 04:25 | ||
| − | |It happens due to a mismatch of '''file name''' and '''class name.''' | + | |It happens due to a mismatch of the '''file name''' and '''class name.''' |
|- | |- | ||
| Line 145: | Line 141: | ||
|- | |- | ||
| 04:39 | | 04:39 | ||
| − | | | + | |creates a file automatically. |
|- | |- | ||
| Line 222: | Line 218: | ||
|- | |- | ||
| 06:58 | | 06:58 | ||
| − | |You can see that once we change it to capital 'S' the error is missing. | + | |You can see that once we change it to capital 'S', the error is missing. |
|- | |- | ||
| 07:06 | | 07:06 | ||
| − | | Here is how you identify errors in Java using '''eclipse''' and rectify them. | + | | Here is how you identify errors in Java, using '''eclipse''', and rectify them. |
|- | |- | ||
| 07:15 | | 07:15 | ||
| Line 258: | Line 254: | ||
|- | |- | ||
| 07:53 | | 07:53 | ||
| − | | The Spoken Tutorial Team conducts workshops using | + | | The Spoken Tutorial Team conducts workshops using spoken tutorials. |
|- | |- | ||
| Line 266: | Line 262: | ||
|- | |- | ||
| 08:07 | | 08:07 | ||
| − | | | + | | Spoken Tutorial Project is a part of the Talk to a Teacher project. |
|- | |- | ||
| 08:11 | | 08:11 | ||
| − | |It is supported by the | + | |It is supported by the National Mission on Education through ICT, MHRD, Government of India. |
|- | |- | ||
Latest revision as of 12:51, 28 March 2017
| Time | Narration |
| 00:01 | Welcome to the tutorial on Errors and Debugging using Eclipse. |
| 00:07 | In this tutorial, we are going to learn: |
| 00:10 | what are the possible errors while writing a simple Java program, |
| 00:14 | how to identify those errors and rectify them using eclipse. |
| 00:20 | For this tutorial, we are using Ubuntu 11.10 and Eclipse 3.7. |
| 00:27 | To follow this tutorial, you must know |
| 00:30 | how to create and run a Java Program in Eclipse. |
| 00:33 | If not, for relevant tutorial, please visit our website as shown. [1] |
| 00:41 | In a simple Java program, the typical errors could be: |
| 00:45 | Missing semicolon(;) |
| 00:47 | Missing double quotes(" ") around the message |
| 00:50 | Mis-match of 'file name' and 'class name' and |
| 00:52 | Typing the print statement in lower-case. |
| 00:55 | We shall write a program and then make each of these errors and see what happens in Eclipse. |
| 01:04 | Here we have the Eclipse IDE and the project used for the HelloWorld tutorial. |
| 01:11 | We shall create a new class in the project and use it. New Class. Let us name the class ErrorFree and select methods stubs public static void main. |
| 01:37 | Let us minimize the package explorer. Remove the comments and add the print statement with a few errors. |
| 02:23 | In Eclipse, the line which has the error will be indicated with a red cross mark on the left margin. |
| 02:35 | In this case, the System.out.println line has an error and hence there is a red cross mark on the left. |
| 02:44 | The list of errors is displayed by hovering the mouse over the cross mark. |
| 02:51 | The first error displayed is: syntax error, insert semi-colon to complete block statements. |
| 02:58 | This is because we have to end every statement of a program with a semicolon. |
| 03:03 | So, let us insert semicolon at the end of the statement. |
| 03:08 | Save the file with Ctrl s. |
| 03:16 | Notice that once we add the semicolon and save the file, the first error is gone. |
| 03:21 | There is only one error now which says: Helloworld cannot be resolved to a variable which means to display any message on the console the message has to be included in double quotes. |
| 03:37 | Without the quotes, Java thinks that HelloWorld is the name of a variable. |
| 03:41 | Let us add double quotes before and after the message. |
| 03:55 | Ctrl s to Save. We see that the red-cross mark is gone and the program is error free. So, let us run the program and see what happens. |
| 04:10 | Run as > Java application |
| 04:15 | We see that the message has been printed on the console. |
| 04:22 | Let us look at the next error. |
| 04:25 | It happens due to a mismatch of the file name and class name. |
| 04:29 | It does not happen usually on Eclipse. |
| 04:31 | This is because we use the New Class wizard to create a file and eclipse |
| 04:39 | creates a file automatically. |
| 04:41 | But, if we create a Java file outside of Eclipse and add it to a project, there is a chance of the error. |
| 04:47 | So, let us stimulate the error by changing the class name. |
| 04:59 | Since Java is case sensitive, now the class name and file name do not match . |
| 05:09 | Notice that there is a red cross mark on the left margin. |
| 05:14 | And error message reads: The public type errorfree must be defined in its own file. |
| 05:20 | Also notice that the word errorfree is underlined in red colour. |
| 05:29 | Eclipse offers intelligent fixes and we have 2 fixes available here. |
| 05:35 | The first one is Rename compilation unit to errorfree java. |
| 05:39 | The second one is Rename the type to errorfree. |
| 05:43 | The fix that we are looking for is the second one. And we see that once you rename the file, the class back to 'ErrorFree', the error here is missing. |
| 06:03 | The next error happens due to typing mistakes in the print statement. |
| 06:09 | Let us replace the capital S with a small s. |
| 06:15 | We notice that there is the red-cross mark |
| 06:18 | and error message reads: system cannot be resolved. |
| 06:23 | This means, Java is expecting a class or object or a variable by the name 'system'. |
| 06:28 | But there is nothing like 'system' object in the code. |
| 06:33 | So, let us look at the possible fixes. |
| 06:39 | There are 11 fixes. Out of these, the fix that we are looking for is the eighth option: |
| 06:48 | Change to 'System' (java.lang). |
| 06:58 | You can see that once we change it to capital 'S', the error is missing. |
| 07:06 | Here is how you identify errors in Java, using eclipse, and rectify them. |
| 07:15 | This brings us to the end of this tutorial. |
| 07:18 | In this tutorial we have seen: |
| 07:20 | what are the typical errors while writing a Java program and |
| 07:23 | how to identify them and rectify them using Eclipse. |
| 07:30 | As an assignment for this tutorial, find out the errors in the code given below and fix them. |
| 07:39 | To know more about the Spoken Tutorial project, |
| 07:42 | watch the video available at the following link. It summarizes the project. |
| 07:48 | If you do not have good bandwidth, you can download and watch it. |
| 07:53 | The Spoken Tutorial Team conducts workshops using spoken tutorials. |
| 07:57 | Gives certificates for those who pass an online test. For more details, please write to contact AT spoken HYPHEN tutorial DOT org. |
| 08:07 | Spoken Tutorial Project is a part of the Talk to a Teacher project. |
| 08:11 | It is supported by the National Mission on Education through ICT, MHRD, Government of India. |
| 08:17 | More information on this mission is available at spoken HYPHEN tutorial DOT org SLASH NMEICT HYPHEN Intro |
| 08:23 | This tutorial has been contributed by TalentSprint.
Thanks for joining. |
Contributors and Content Editors
Gaurav, Madhurig, PoojaMoolya, Pravin1389, Sandhya.np14, Sneha
