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Thread: Need help with Vectors

  1. #1
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    Default Need help with Vectors

    This is my first time doing vectors in Java and I am a bit rusty at java as it is and would appreciate any help.
    I have to have a method called
    boolean addGroup(Vector objects, int start) – This method adds the elements in the vector argument to the list, starting at position start in the list and preserving the vector order. Be mindful of the CPU performance of your solution. You may assume that the list/array will always be big enough to take the additional objects.

    This is what i have done so far in LinkList
    public boolean addGroup(Vector<Object> objects, int start)
    {
    boolean result = false;
    {
    Vector<Object>a = new Vector<Object>();
    a.addAll(objects);
    result = true;
    }
    return result;
    }
    Test:
    public void testAddGroup()
    {
    populateList();
    assertTrue(lList.getLength() == 2);
    populateVector();
    boolean result = lList.addGroup(films, 1);
    assertTrue(result);
    assertTrue(lList.getLength() == 8);
    assertEquals(film3, lList.getEntry(3));
    assertEquals(film7,lList.getEntry(7)) ;
    assertNull(lList.getEntry(9)) ;
    }
    I have created a method called populateVector() to make it easier for making my test class:
    private void populateVector()
    {
    films.add(film3);
    films.add(film4);
    films.add(film5);
    films.add(film6);
    films.add(film7);
    films.add(film8);
    }
    Last edited by Locky; October 18th, 2010 at 08:48 AM.


  2. #2
    Crazy Cat Lady KevinWorkman's Avatar
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    Default Re: Need help with Vectors

    What's your question?

  3. #3
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    Default Re: Need help with Vectors

    My question is what can I do to make my code work. I have ran it in the test and it has just failed. I have been at this for quite a while and since it's my first time doing Linked Lists and Vectors I am very confused.

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    Default Re: Need help with Vectors

    Quote Originally Posted by Locky View Post
    My question is what can I do to make my code work. I have ran it in the test and it has just failed. I have been at this for quite a while and since it's my first time doing Linked Lists and Vectors I am very confused.
    Run a debugger to figure out where your code is different from what you expect. Get it narrowed down to a couple lines, then ask a specific question.

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    Default Re: Need help with Vectors

    Thats the problem. I am unsure where I am going wrong as this is my first attempt at Linked List and also at Vectors.
    I know this code is wrong but I would like to know if I have done anything right:

     public boolean addGroup(Vector<Object> objects, int start)
    {
    boolean result = false;
    {
    Vector<Object>a = new Vector<Object>();
    a.addAll(objects);
    result = true;
    }
    return result;
    }
    Last edited by Locky; October 18th, 2010 at 10:20 AM.

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    Default Re: Need help with Vectors

    Your posted code is missing quite a bit of information, and posting where it fails in the test will help explain what the problem is. Based upon what you have so far, you add all the parameter objects to a Vector which has the scope of the addGroup function eg the vector is lost as soon as the function exits, which I presume is not the behavior you wish.

  7. The Following User Says Thank You to copeg For This Useful Post:

    Espressoul (October 19th, 2010)

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    Default Re: Need help with Vectors

    Did you get it sorted and submitted after Jay?

    Nice tip on using a debugger copeg, figured out how to set a breakpoint and step through/over methods to see how they work. Always wanted to see a method go through each step and watch the cogs turn, will be handy in future.

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