Thread: IndexOutOfBounds.. Error

Hey guys, I just joined the forums and hope to learn a lot about programming here.

So, I have an assignment to make a code calculating the mode of a text file with 999 integers. I know there are probably more efficient ways to solve this problem, but I want to stick with my code and just fix it. I'm trying to make one ArrayList with the occurrences(frequencies) of each of the 999 integers in the text file, and get the mode that way.

I keep on receiving this error
"IndexOutOfBoundsException: Index: 1, Size: 1)"
when I try to run my code, and the highlighted error is on my "numbers.remove..." and on "backUp.remove..." in my public intCalcFinalMode() method. I know what the error means, but I've tried everything and I cannot find a way to fix it. Can someone please point out my error? Thanks.

import java.util.ArrayList; import java.lang.Math;     public class Statistics { private ArrayList<Integer> numbers = new ArrayList<Integer>(); private ArrayList<Integer> occurrences =new ArrayList<Integer>(); private ArrayList<Integer> finalMode = new ArrayList<Integer>(); private ArrayList<Integer> backUp = new ArrayList<Integer>();   public Statistics() { } //end default constructor   public Statistics(ArrayList<Integer> inputNumbers) { numbers = inputNumbers; } //end non-default constructor public void calcOccurrences() {   for(int currentNumber : numbers) { int counter = 0; int numberOfOccurrences = 0; while (counter < numbers.size()) { if (currentNumber == numbers.get(counter)) { numberOfOccurrences++; counter++; } else { counter++; } //end if         } //end while statement occurrences.add(numberOfOccurrences); backUp.add(numberOfOccurrences);   } //end extended for loop } //end method   public int calcFinalMode() {     for(int currentOccurrence : occurrences) { int facto=0; int counter = 0; while (counter < occurrences.size()) { if (currentOccurrence >= occurrences.get(counter)) { counter++;     } else {   [B]numbers.remove(occurrences.indexOf(currentOccurrence)); backUp.remove(occurrences.indexOf(currentOccurrence));[/B] } //end LONG if   } // end while loop facto = numbers.get(backUp.indexOf(currentOccurrence)); finalMode.add(facto);   } //end extended for loop   return finalMode.get(0);   } //end method   public int calcOtherMode() { int otherMode = 0; finalMode.remove(0); if (!finalMode.isEmpty()) { otherMode = finalMode.get(0); } //end if statment return otherMode; } //end method     } //end class   DRIVER --------------------------------   import java.io.File; import java.io.IOException; import java.util.ArrayList; import java.util.Scanner;   public class StatisticsDriver { public static void main(String args[]) { ArrayList<Integer> numbers = new ArrayList<Integer>();   Scanner in; try { in = new Scanner(new File("numbers.txt")); while(in.hasNextInt()) { numbers.add(in.nextInt()); } //end while loop   } catch(IOException i) { System.out.println("Error: " + i.getMessage()); } //end file-read   Statistics myStatistics = new Statistics(numbers); myStatistics.calcOccurrences(); System.out.println("Mode: " + myStatistics.calcFinalMode() + ", " + myStatistics.calcOtherMode());   }// end main   } //end class

Hello Arius.

When I compile this code I don't get any errors? I ran it against my own version of numbers.txt and get this output:

Mode: 1, 1

What would you expect the output to be?

Could you please attach your version of numbers.txt. I need to try to replicate the error...

[ATTACH]numbers.txt[/ATTACH]

I think I just uploaded it. I know for a fact that the two modes for this text file are 10 and 48. When you ran your version of numbers, it gave you the correct mode? That is odd.

In researching the solution for this problem, I actually found that you cannot remove inside of a for loop, so I revised me code as well. If you can correct the problem on either one and make the modes (10, 48) actually appear, I will be eternally grateful, since I've been working on this for 5 days straight with no success. However, I know some methods such as hash and etc are more effective, my assignment requires that I stick with only array lists and no more importations... Thank you.

import java.util.ArrayList; import java.lang.Math;     public class Statistics { private ArrayList<Integer> numbers = new ArrayList<Integer>(); private ArrayList<Integer> occurrences =new ArrayList<Integer>(); private ArrayList<Integer> finalMode = new ArrayList<Integer>(); private ArrayList<Integer> backUp = new ArrayList<Integer>();   public Statistics() { } //end default constructor   public Statistics(ArrayList<Integer> inputNumbers) { numbers = inputNumbers; } //end non-default constructor   public double calcAverage() { int total = 0; for(int currentNumber : numbers) //don't need to specify size cuz goes for duration of arraylist { total += currentNumber; } //end extended for loop   return (total/numbers.size());   } //end method   public double calcStandardDeviation() { double total = 0; for(int currentNumber : numbers) { double partOfSum = Math.pow((currentNumber - calcAverage()), 2); total += partOfSum; } //end extended for   return Math.pow((total/(numbers.size() - 1)), 0.5);   } //end method   public void calcOccurrences() {   for(int currentNumber : numbers) { int counter = 0; int numberOfOccurrences = 0; while (counter < numbers.size()) { if (currentNumber == numbers.get(counter)) { numberOfOccurrences++; counter++; } else { counter++; } //end if         } //end while statement occurrences.add(numberOfOccurrences); backUp.add(numberOfOccurrences);   } //end extended for loop } //end method   public void calcFinalMode() {     for(int currentOccurrence : occurrences) {   int counter = 0; while (counter < occurrences.size() && counter > 0) { if (currentOccurrence >= occurrences.get(counter)) { counter++;   } else { numbers.set((occurrences.indexOf(currentOccurrence)), 0); backUp.set((occurrences.indexOf(currentOccurrence)), 0); counter = 1000;   } //end LONG if   } // end while loop if (!(currentOccurrence == 0)) { int facto = numbers.get(backUp.indexOf(currentOccurrence)); finalMode.add(facto); } // end if int facto=0;     } //end extended for loop   } //end method   public int calcDefMode() { int counter = 0; int facto = 0; while (counter < finalMode.size()) { if (finalMode.get(counter) > 0) { facto = finalMode.get(counter); counter = 1000; } //end if statment } //end while return facto; } //end method         } //end class

DRIVER -------------------------------------------------------- import java.io.File; import java.io.IOException; import java.util.ArrayList; import java.util.Scanner;   public class StatisticsDriver { public static void main(String args[]) { ArrayList<Integer> numbers = new ArrayList<Integer>();   Scanner in; try { in = new Scanner(new File("numbers.txt")); while(in.hasNextInt()) { numbers.add(in.nextInt()); } //end while loop   } catch(IOException i) { System.out.println("Error: " + i.getMessage()); } //end file-read   Statistics myStatistics = new Statistics(numbers); //why can't put "ArrayList inputNumbers"???? System.out.println("Average: " + myStatistics.calcAverage()); System.out.println("Standard Deviation: " + myStatistics.calcStandardDeviation()); myStatistics.calcOccurrences(); myStatistics.calcFinalMode(); //System.out.println("Mode: " + myStatistics.calcFinalMode() + ", " + myStatistics.calcOtherMode()); System.out.println("Mode: " + myStatistics.calcDefMode());   }// end main   } //end class