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Thread: Matlab / Java Linked List Error

  1. #1
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    Default Matlab / Java Linked List Error

    i'm working on my Final university Project , and my time is too short the project is about Wireless sensor network and i have to simulate one of the recent papers about it. most of the coding is done but i have a simple problem about linked list(i use matlab and import java libraries into it for using linked list)

    okay here is some explanation i have a queue/list that every time head of the list is checked that is it the goal or not if its not a goal it deletes the first item and gets the second one which is actualy the first one in the list problem occurs when my list has only 1 item and its not goal so code delete the first item , AFTER that code tries to get the first item which is null and empty thats when Error happens ,

    my goal is after checking/searching all the list if it was successful turn flagg=1 if not flagg=0

    while temp ~= goal;

    for K=1:size(G,1)

    if temp == G(K,1)


    if (~q.isEmpty())




    Thanks. M.Dadmand

  2. #2
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    Default Re: Matlab / Java Linked List Error

    What happens when the list only has a single element? Trace through this with a piece of paper and a pencil if you have to.
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    Default Re: Matlab / Java Linked List Error

    thank you so much for reply
    let me explain more
    first my search is Breadth first search

    if the algorithm find the goal it will break the While and everything is fine
    but at the moment no result has found (that means the queue is empty)

    i have a matrix like this :
    [1,2; 1,3 ; 1,5 ; 3,8 ; 5,10]

    i input 1 by hand for the first number in queue
    it searches the 1 in my matrix (only the first column) we have 3 ones in our first column
    so it add 2 , 3 , 5 to the queue
    after finish searching in my matrix it deletes the first one (q.removeFirst()
    and gets the first one so now is 2
    loop repeats until we are at 10 and no goal found yet
    so at this line :

    it removes 10 and tries to get first item which is nothing/null and that's when error happens
    so what i want to do after that is turn a flag 1 and come out of my while loop

    if i use poll method instead of these

    lines everything could work fine , saddly matlab gives me this error for it
    Undefined function 'pollFirst' for input arguments of type 'double'.

    Error in TestFInal2 (line 102)

    EDIT : problem solved , i just added a break in while

    so it breaks the while NOT the whole code
    btw i was stuck at in in weeks
    i have another problem its about graph should i make another thread ?

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