Rolling 2 six sided dice 1000 times, unexpected results

When simulating rolling 2 dice 1000 times and displaying the result, it keeps returning unexpected values. My program is:

import java.util.*;

public class Prob1 {
    private int sides; //Amount of sides on die
    private int sumOfRolls; 
    private int[] arr; //Array that holds the count of each sum of the rolls
    private int count; //Temporarily holds value of sum of rolls before passing to array
    public Prob1() { //Default constructor, sets sides to 6
        sides = 6;
        sumOfRolls = 0;
        count =0;
        arr = new int[(sides*2)+1];
    }
    public void roll() { //Method that rolls the 2 dice
        for(int i=0;i<1000;i++) { //Repeats 1000 times
            int roll1 = (int) (Math.random()*sides)+1; //Rolls 1 die
            int roll2 = (int) (Math.random()*sides)+1; //Rolls other die
            sumOfRolls = roll1+roll2; //Sums both rolls
            for(int j=2;j<(sides*2)+1;j++) { //Goes through all the possible values of sums of roll
                if(sumOfRolls==j) { //Checks if sum of rolls is equal to the value presented by the for loop
                    count++; //Adds 1 to count of value of sum of roll
                    arr[j]=count; //Adds that value to array
                }
            }
        }
        System.out.println("Roll: " + sides + "-sided dice"); //Displays what kind of dice
    }
    public void frequency() { //Frequency table
        System.out.println("\n\n\nRoll Total  Frequency");
        System.out.println("---------------------");
        for(int i=2; i<(sides*2)+1; i++) { //Displays each value of array
            System.out.print(i + "           " + arr[i] + "\n");

        }

    }


}

When both the roll and frequency methods are called, this is the result:

Roll: 6-sided dice



Roll Total  Frequency
---------------------
2           952
3           995
4           976
5           989
6           991
7           999
8           1000
9           998
10           992
11           994
12           997

This is erroneous, as the sum of each value exceeds 1000, the number of times the two dice are rolled. Is there any fix to this?