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Thread: Help with Assignment

  1. #1
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    Default Help with Assignment

    Hi folks. I am currently studying Computer Science and one of the modules I am taking at the moment is Concurrent & Distributed Systems. My first assignment involves using await statements and semaphores for a train track using Eclipse. I have wrote out code but it has many errors. The link below shows the assignment question and below that is the code I have written so far. Can anyone assist me in completing this assignment? I would be very grateful

    https://docs.google.com/viewer?a=v&q...yDbwCEKc0Z8IcA

    Code
    Global Invariant: (NumberOfTrainsInAnySection <= 1) AND (TotalTrainsOnTrack <= 8)
    Process main {
    	/* Declare and initialize global variables */
    Const Number_Of_Trains = 10;
    Int NumberOnTrack =0;
     
    /* sections on the traintrack */
    string  sections[0..10]  =  {“[.....]”, “[.....]”, “[.....]”, “[.....]”, “[.....]”, “[.....]”, “[.....]”, “[.....]”,“[.....]”, “[.....]”, “[.....]”, “[.....]”, };
     
    //* Set the train moving 
    	 for (count= 1 to NUMBER_OF_TRAINS){
    		int entry= {0...0}; 
                       	int exit = { 0...11 }; 
                       	TrainProcess (entry,  exit);
                   } /* end  for *
    } /* end main process
     
    // Train Process
    process TrainProcess (int s, int t) {
     /* Wait if track is too crowded
    <await (numberOnTrack<=8) numberOnTrack++; >
        /* wait for section 1 to be clear from the right side
         <await ( (section[1]==”[.....]”) section[1]=”[“+entry+”-->”+exit”]”;>
        /* move forward to exit position (which is 10s) */
        int currentPosition = 0*s;
        int nextPosition = 0*s+1;
        do   {
           <await (sections[nextPosition]==”[.....]”)  sections[nextPosition]=sections[currentPosition]; 
                              sections[currentPosition]=”[.....]”; >
           currentPosition = nextPosition;
           nextPosition = (nextPosition+1) SECTIONS 8;
        } while (currentPosition <> 2*t)
       /* move off the track*/
       < slots[currentPosition]=”[.....]”; numberOnTrack-->
    } /* end TrainProcess


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Help with Assignment

    Can you explain what problems you are having?

    Please edit your post and wrap your code with
    [code=java]
    <YOUR CODE HERE>
    [/code]
    to get highlighting and preserve formatting.
    If you don't understand my answer, don't ignore it, ask a question.

  3. #3
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    Default Re: Help with Assignment

    Well the main process is for the trains to travel safely on the track and an await statement is required for the trains to cross over the junction safely. I think that I have declared the improper global variables and my await statements in the Train Process section is wrong also. Could anyone help me to correct it?

  4. #4
    Super Moderator Norm's Avatar
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    Default Re: Help with Assignment

    Do you have a java program you are working on? The posted code is not valid java code.
    If you don't understand my answer, don't ignore it, ask a question.

  5. #5
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    Default Re: Help with Assignment

    I have written this code in Eclipse. Because I'm not that good at Java (or programming in general) the code is probably mixed up.

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    Default Re: Help with Assignment

    Quote Originally Posted by docguy89 View Post
    I have written this code in Eclipse. Because I'm not that good at Java (or programming in general) the code is probably mixed up.
    You have completely invalid syntax in there, which makes it very hard to determine exactly what you're asking. I recommend fixing the syntax and compiler errors and creating an SSCCE that demonstrates the smallest piece of the program you're working on.
    Useful links: How to Ask Questions the Smart Way | Use Code Tags | Java Tutorials
    Static Void Games - Play indie games, learn from game tutorials and source code, upload your own games!

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    Default Re: Help with Assignment

    Yep, your first step will be to learn basic Java syntax which you can do at the Java tutorials that are linked to in Kevin's "useful links" signature links above, or which you can find here. You can't guess at this stuff and pray that it might work, and we'll not be able to help you til you've taught yourself at least some of the rudiments of the language. Also contact your instructor to schedule some intense one-on-one counseling as you have a lot of catching up to do, it appears.

  8. #8
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    Default Re: Help with Assignment

    The assignment has to be in for today and I still cannot get it working

  9. #9
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    Default Re: Help with Assignment

    an await statement is required
    There is no await statement in java.
    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: Help with Assignment

    Quote Originally Posted by Norm View Post
    There is no await statement in java.

  11. #11
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    Default Re: Help with Assignment

    Recode the project in java.
    If you don't understand my answer, don't ignore it, ask a question.

  12. #12
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    Default Re: Help with Assignment

    Yes I understand. The code listed in my first post is the algorithm, all I have to do now is implement it using Eclipse. Can any of you guys help me to implement it?

  13. #13
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    Default Re: Help with Assignment

    What have you got for a design for the program?
    Do you have any java code written for some of the steps in your design?
    If you don't understand my answer, don't ignore it, ask a question.

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