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Java Forum / First Aid / November 2005Help needed with BlueJ
Hi All, Need help(procedures/steps) to execute an application program using BlueJ. I have downloaded the BlueJTutorial.pdf, read what is there, I can compile my program, can make a jar, but where is the "run" instruction in the main menu? Bob There isnt a "run" instruction as such, you have to go to File, then "export" then save it as a jar file then open the jar file from where you exported it to. www.bluej.org may have some help on it though. Any more problems let me know because David Barnes and Micheal Kolling (the BlueJ authors) are lecturers at my uni so they are bound to be able to help. JS > Hi All, > Need help(procedures/steps) to execute [quoted text clipped - 7 lines] > > Bob Hi JS, Thanks for help. I have never been comfortable with x.jar as such because of the near primitive means to get them to execute an application and the complicated methods to create paths to the X.class files and image files that accompany it. Since BlueJ has automated this .jar making then that problem seems to be eliminated. You might ask the authors of BlueJ how to deal with this problem: When I work on code, I like to see if something needs an adjustment/tweak of this or that for appearance sake and the like. That is why I "would like to see it sooner" than before it is ready to "hand in for final grading in a jar". Or is it a matter of constanly modifying the version name of the program that you are writing and then keep tossing out the older jars for the new one? Thanks again for your help, Bob > I have never been comfortable with x.jar as such because of the > near primitive means to get them to execute an application and the [quoted text clipped - 9 lines] > modifying the version name of the program that you are writing and then > keep tossing out the older jars for the new one? I have read that several times but still do not quite understand what you are saying. OTOH, I will make this point. Whether deploying as a Jar or (much less often) a series of class files, developers almost always have easy access to throwing a 'work in progress' onto the screen to check the current changes. They would have a hard time developing without that easy ability. Either it should be very easy to create an launch a Jar from the IDE, or alternately launch the application using the unjarred class files. Is 'Seeing the application on-screen after changes' the basic nature of the problem? BlueJ is not a normal IDE. It is specifically designed as a teaching tool, not a production tool. It focuses on visual representations of objects to better help the student understand OOP concepts. In BlueJ, for example, you can instantiate an object, call its methods, and see the changes in its instance variables visually WITHOUT the need to write a main method. However, some things that are simple in a traditional IDE (or even from the command line) are not that simple in BlueJ. For example, in most IDE's, there is a button that will execute an application, but not in BlueJ. It is a popular teaching tool worldwide, but it is NOT something that an actual developer would use. Thanks Andrew and Redbeard, Maybe for the same reasons that I tossed BlueJ before: "jar it to see it run" doesn't make sense to me. These other lightwieghts have flaws too: DrJava doesn't jar anything by itself. GEL gets mixed up in its delivery and storage. And JBuilder2005 overstuffs my computer. At this point, as I have jdk1.5.0_05, any recommendations from either of you for all around lightwieght IDE? Bob You can run classes and things without making them into a jar because all you need to do is compile them then right click on the class you want to use and selecting the "constructor (s)" shown. you can create as many classes as you want that way. Also be careful creating jars with images. The version we had, and I'm not sure if this has changed, only allowed us to include images OR include a main method which made it runnable. we all found that out when we had an assignment due and he neglected to tell us that so we were all panicking about the file. It does have a very useful debugger and step through tool which no other Java IDE I have seen does have. I was tempted to write my own but I'm not sure how as yet and also havent really got time on my side what with other projects that have more deadlines. Any ideas from anyone or if anyone wants to work on one with me feel free to contact me. I now use JCreator which I found to be pretty good. I'm not sure how it works when it comes to jar files or javadocs yet because we mainly have to submit .java and .class files for uni work but there must be a way. Netbeans and Eclipse are also pretty good so I've heard but I havent really looked at them and they are quite memory intensive on some machines. Hope that helps and if anyone has any ideas then feel free to get in touch JS > Thanks Andrew and Redbeard, > [quoted text clipped - 11 lines] > > Bob JS, Your clues: after compiling (above)..... Are you thinking that there is something that I can right click on the BlueJ panel or is this some place else. Frankly, I don't see except in the outermost frame of BlueJ: a white empty frame and the yellow-orange shaded frame of the .java named program that are loaded . And after compiling the right click on the yellow-orange shaded frame sets a red box in the lower left and right clicking on it does nothing. I have version 2.05 of BlueJ. Bob, There is no need to create a jar file to execute something in BlueJ. You can execute any program directly from within BlueJ. In fact, you can execute more than in other IDEs: you can execute the main method (as in other environments) or any other public method. To execute the main method (if you have one), right-click the class in the diagram (the "yellow-orange thingy") and select the main method from the popup menu. To execute other (non-static) methods, right-click the class, select a constructor, and then right-click the created object (the "red box") and select your methods. This is described in much more detail in the tutorial. I suggest that you read it again and work through it. Especially section 3.4 ("Execution") and section 10.3 ("Calling main and other static methods"). Regards, Michael > Hi JS, > Thanks for help. [quoted text clipped - 16 lines] > > Bob To run it as an application, you need a "main class" with a method: public static voin main(String[] args) { Once you have written this method, you can start the application from within BlueJ by right-clicking the class icon that contains this method, and choosing that method from the pop-up list. You will be prompted to supply the String[] argument. Steve Michael, Steve, and All, Thanks for the help, I appreciate it. While reading the BlueJ Tutorial, my mind was focused on the idea that this was "prescriptive" with assurances this is the way it was to look. I failed to read: "you should see something similar to the window shown in Figure 1 except on your machine ... the differences should be minor. For the record here: Using a sample java application program of mine, titled "lab1", and after compilation, right clicking the title bar of the application on the main page that has the diagram (the "yellow-orange thingy") brings a pop up with many choices. Selecting from the list of choices with a left or right click: "void main(Strings[] args) " and from the next popup window which appears as: BlueJ: Method Call void main(Strings[] args) lab1.main({ }) Note: I made no changes in the entry of the "{ }". Clicking OK does a "execute" or a "run" of the java program. Thanks again to all for responding. Bob Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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