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POMy bubble sort over a double linked list cuts off the first node of the list for some reason
 

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  1. POMy bubble sort over a double linked list cuts off the first node of the list for some reason
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    <p>Here's the method</p> <pre><code>public void sortStudentsAlphabeticallyByFirstName() { StudentNode unsorted = tail; StudentNode current = header; while(unsorted.prevNode() != null) { while(current != unsorted) { int result = (current.getFirstName()).compareToIgnoreCase(current.nextNode().getFirstName()); if(result &gt; 0) //If in wrong order lexicographically { StudentNode temp = current; StudentNode next = current.nextNode(); StudentNode previous = current.prevNode(); StudentNode nextNext = next.nextNode(); if (numberOfStudents() == 2) { current = current.nextNode(); current.setNext(temp); temp.setPrev(current); temp.setNext(null); current.setPrev(null); unsorted = temp; } else if(nextNext == null) //If at penultimate student therefore last comparison { current = current.nextNode(); current.setNext(temp); temp.setPrev(current); temp.setNext(null); previous.setNext(current); current.setPrev(previous); unsorted = temp; } else if(previous == null) //if at beginning of student list { if(current.nextNode() == unsorted) { current = current.nextNode(); current.setNext(temp); temp.setPrev(current); temp.setNext(nextNext); nextNext.setPrev(temp); current.setPrev(null); unsorted = temp; //swap unsorted back to correct position } else { current = current.nextNode(); current.setNext(temp); temp.setPrev(current); temp.setNext(nextNext); nextNext.setPrev(temp); current.setPrev(null); } } else //else if in the middle of the list { if(current.nextNode() == unsorted) { current = current.nextNode(); current.setNext(temp); temp.setPrev(current); temp.setNext(nextNext); nextNext.setPrev(temp); previous.setNext(current); current.setPrev(previous); unsorted = temp; } else { current = current.nextNode(); current.setNext(temp); temp.setPrev(current); temp.setNext(nextNext); nextNext.setPrev(temp); previous.setNext(current); current.setPrev(previous); } } } current = current.nextNode(); } current = header; unsorted = unsorted.prevNode(); } } </code></pre> <p>Can anyone see why it cuts off the beginning of the list when I try to iterate the list again? I've used the debugger and it seems to run like it should, but I can't work out why it's doing it.</p> <p>Here's the iterate list method as well if it helps</p> <pre><code>public void itterateList() { StudentNode u = header; while(u != null) { System.out.println(u.getFirstName()+" "+u.getSurname()); u = u.nextNode(); } } </code></pre>
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    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. USuser207421
    1. USDave Shaw
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
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      1. PTAnswer
    1. VO
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      1. POMy bubble sort over a double linked list cuts off the first node of the list for some reason
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POMy bubble sort over a double linked list cuts off the first node of the list for some reason
      1. This table or related slice is empty.
      1. VTUpMod
    1. COBubbleSort. Don't get me started!
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      1. POMy bubble sort over a double linked list cuts off the first node of the list for some reason
      1. USMitch Wheat
    2. COYou shouldn't iterate through the original variable but through temp only. Since it references it, saying next on that would be the same as saying next to current. That way you keep the head at all times, and untouched.
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      1. POMy bubble sort over a double linked list cuts off the first node of the list for some reason
      1. USAndy
    3. CO@Andy Sorry I don't quite get what you mean. Which original variable?
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      1. POMy bubble sort over a double linked list cuts off the first node of the list for some reason
      1. USDave Shaw
 

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