N-queens with stacks

Question

trying to solve the classic "8-queens" (http://en.wikipedia.org/wiki/Eight_queens_puzzle) problem with a stack, but I can't seem to get it working right. For now, I'm just trying to get it to print out one solution. Here is the code so far. At the moment, it prints out a 6x6 grid for some reason instead of an 8x8, and some of the queens are diagonal from each other. Point out problems or solve it if you can.
import java.util.Stack;
public class Assignment3{
    static int numSol=0;
    static int curCol;
    public static int solve(int n) {
     Stack<Integer> s = new Stack<Integer> ();
     for(int row=0; row<n;row++){
         for(int col=0; col<n;col++){
          if(conflict(row,col,s)==false){
              s.push(col);
              System.out.println(row);
              if (row == (n-1)){
               printSolution(s);
               numSol++;
              break;
          }else{
              if(col==(n-1)){
               row=row-1;
               col=s.pop();
     return numSol;
    public static boolean conflict(int row, int col,Stack<Integer> s){
     boolean conflicts =false;
     for(int pastRow=0; pastRow<s.size(); pastRow++){
         curCol = s.get(pastRow);
         if(curCol == col || curCol-pastRow == col-row || curCol+pastRow == col+row){
          conflicts = true;
          break;
          return conflicts;
    //this method prints out a solution from the current stack
    //(you should not need to modify this method)
    private static void printSolution(Stack<Integer> s) {
     for (int i = 0; i < s.size(); i ++) {
         for (int j = 0; j < s.size(); j ++) {
          if (j == s.get(i))
              System.out.print("Q ");
          else
              System.out.print("* ");
         }//for
         System.out.println();
     }//for
     System.out.println(); 
    }//printSolution()
    public static void main(String[] args) {
     int n = 8;
     if (args.length == 1) {
         n = Integer.parseInt(args[0].trim());
         if (n < 1) {
          System.out.println("Incorrect parameter");
          System.exit(-1);
     int number = solve(n);
     System.out.println("There are " + number + " solutions to the " + n + "-queens problem.");
}

Answer 1

There's little to say apart from general advice. Create tests to exercise your code under new conditions and not requiring direct user interaction. Your code looks reasonably well composed, which should make that easier; the only issue are those static fields -- can you make those local variables instead?
Then add some debugging statements to see where things are going wrong.