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Thread: Removing duplicates from an array

  1. #1
    Junior Member
    Join Date
    Oct 2013
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    Default Removing duplicates from an array

    I have some code to build an object elementData that stores a list of ints in an array and also keeps track of a boolean unique that determines if duplicates are allowed in a list. I have written a small method to search out duplicates and remove them, but for some reason it is not working. I am not sure if the problem is with the method itself or the placement of the call to the removeDuplicates method.

       // post: places the value in the correct place based on ascending order
       public void add(int value) {
          if (size == 1) {  
             elementData[0] = value;
          } else {
             int position =  Arrays.binarySearch(elementData, 0, size - 1, value);
             if (position < 0 ) {
                position = (-position) - 1;
             for (int i = size - 1; i > position; i--) {
                elementData[i] = elementData[i - 1];
             elementData[position] = value;
             if (unique) {
       //post: removes any duplicate values from the list
       private void removeDuplicates() {
          for(int i = size - 1; i < 0; i--) {
             if (elementData[i] == elementData[i - 1]){
       // pre : 0 <= index < size() (throws IndexOutOfBoundsException if not)
       // post: removes value at the given index, shifting subsequent values left
       public void remove(int index) {
          for (int i = index; i < size - 1; i++) {
             elementData[i] = elementData[i + 1];

  2. #2
    Super Moderator
    Join Date
    Jun 2013
    So. Maryland, USA
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    Thanked 698 Times in 680 Posts

    Default Re: Removing duplicates from an array

    Show a sample run that prints the list first filled and then after the attempt to remove duplicates.

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