ArrayList throwing "java.lang.ArrayIndexOutOfBoundsException"

Question

I know from reading other questions on the forumn that Array indexing is causing the problem, but I don't know any way around it. I commented where the throw happens. The whole throw is

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 35
at assignment4.AnagramUtil.getLargestAnagramGroup(AnagramUtil.java:82)
at assignment4.AnagramTester.main(AnagramTester.java:36)

If anyone has any ideas how I can make this work, let me know. Also, I don't think any more of my methods are relevant in solving this but I can put them here if needed.

    /*areAnagrams
     * parameters: sorted strings x & y
     * returns boolean
     * implements sort method
     */
    public static boolean areAnagrams(String x, String y)
    {
        if(sort(x).equals(sort(y)))
            return true;
        return false;
    }


    /*
     * This function takes a string array and finds the largest anagram group.
     * AnagramComparator.insertionSort() sorts the array by placing anagrams together,
     * so no sorting is needed.
     * I use ArrayList because I want to be able to freely add to the string array.
     * returns a new String[]
     */
    public static String[] getLargestAnagramGroup(String[] input)
    {
        String[] s=input;

        AnagramComparator.insertionSort(s, new AnagramComparator());

          int largestCount = 0, tempCount=1;
          ArrayList<String> largest= new ArrayList<String>();
          ArrayList<String> temp= new ArrayList<String>();

          for(int i=0; i<s.length; i++)
          {
              //since it's already sorted, we need only to compare.
              //add 
              temp.add(s[i]);
                                            //Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 35
              if (areAnagrams(s[i],s[i+1]))  //at assignment4.AnagramUtil.getLargestAnagramGroup(AnagramUtil.java:82)
              {
                  //add s[i+1] to array list
                  temp.add(s[i+1]);
                  tempCount++;
              }
              else
              {

                    //if tempcount> largestcount, empty contents of largest and make temp largest

                    if (tempCount>largestCount)
                    {
                        if(!largest.isEmpty())
                            largest.clear();
                        largest=temp;
                    largestCount=tempCount; 
                    }
                    //reset tempcount
                    tempCount=1;
              }

          }

     String[] result= new String[largest.size()];

     for (int j=0;j<largest.size();j++)
         result[j]=largest.get(j);
                return result;


    }

What happens with this line when i = length-1; temp.add(s[i+1]); — duffymo
– duffymo, Commented Feb 14, 2015 at 3:38
I use String[] s= input so the insertionsort doesn't affect the input. — Jawsh Bivens
– Jawsh Bivens, Commented Feb 14, 2015 at 3:49
@JawshBivens references do not work that way. String[] s = input copies the reference, not the array - now input and s both contain references to the one array. — Stack Exchange Broke The Law
– Stack Exchange Broke The Law, Commented Feb 14, 2015 at 5:42

Epicblood · Accepted Answer · 2015-02-14 03:40:41Z

3

your problem is here:

areAnagrams(s[i],s[i+1])

this will fail when i = s.length - 1 because of i + 1 (when i = s.length it is out of bounds, as length returns the number of elements, yet array index starts at 0)

change

for(int i=0; i<s.length; i++)

to

for(int i=0; i<s.length - 1; i++)

answered Feb 14, 2015 at 3:40

Epicblood

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duffymo · Accepted Answer · 2015-02-14 03:39:17Z

2

Try changing this line:

for(int i=0; i<s.length; i++)

to this:

 for(int i=0; i<s.length-1; i++)

answered Feb 14, 2015 at 3:39

duffymo

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Paul Richter · Accepted Answer · 2015-02-14 03:43:28Z

0

You have a loop

for(int i=0; i<s.length; i++) {...

which means that for the maximum allowable value of i, s[i] will be the last element in s.

But within the loop you are referencing s[i + 1], which is past the end of s.

answered Feb 14, 2015 at 3:43

Paul Richter

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