Logic error(I cant make it do what i want) plz help

Question

im writing a program for my lab at school and i cant figure out how to make it work. i thought i had figured it out, its close but not all the way there. im supposed to write a program in which 2 dice are rolled and the sum is added up. the dice should continue to be rolled until i get all possible sums ( 2 to 12) and it should display how many tries it took. this whole process should be repeated as many times as the user wants to play. it works fine the 1st tiime but after that it keeps printing out 0. anywhere heres how i have it written.public void rollForSum(int trials) {
        sum = value1 + value2;
        counter = 2;
        counter2 = 0;
        counter3 = 1;
        while (counter3 <= trials) {
            while (counter <= 12) {
                while (sum != counter){
                    value1 = 1 + generator.nextInt(6);
                    value2 = 1 + generator.nextInt(6);
                    sum = value1 + value2;
                    counter2++;
            counter++;
        System.out.println("It took " + counter2 + " times");
        counter2 = 0;
        counter3++;
}

Answer 1

Well I can see you've had a go, so good on you, but there are several problems.
You seem to be doing your counter incrementing in the wrong places, and in any case, you'd be better to use "for" loops for the fixed loops because they make the functionality clearer - something like this:public void rollForSum(int trials) {
        int tries = 0;
        for (int trial = 0 ;  trial < trials ; trial++) {
             for (int diceTot = 2 ; diceTot <= 12 ; diceTot++) {
                 do {
                    value1 = 1 + generator.nextInt(6);
                    value2 = 1 + generator.nextInt(6);
                     sum = value1 + value2;
                     tries++;
                 } while (sum != diceTot);
             System.out.println("It took " + tries + " times");
}However, I don't think this actually does what you want, because you are counting the number of tries to get a 2, then the number of tries to get a 3 and then the number of tries to get a 4, and so on up to 12. I suspect what you really should be doing is count the number of tries to get at least one of each number. To achieve that, you need to hold a flag saying whether you have found each number separately, and a counter of the numbers found so far.
I would do this by holding an array of booleans and a counter then you only need two loops, one "for" loop for trials, and an inner "while" loop (like you used) like this:int tries = 0;
for (int trial = 0 ;  trial < trials ; trial++) {
  boolean[] sums = new boolean[13];
  int sumsFound = 0;
  while (sumsFound < 11) {
    value1 = 1 + generator.nextInt(6);
    value2 = 1 + generator.nextInt(6);
    sum = value1 + value2;
    tries++;
    if (!sums[sum]) {
      sums[sum] = true;
      sumsFound++;
}Hope this helps!
Regards,
Tim