Help with sort function

[Joel Allison]

I'm writing a program that is supposed to sort data by population, and by alphabetical order. I can't get it to work though, I think it is specifically my sort functions.

 static void sortByPopulation(String[] a, double[] b,int n)
{
  int last, x, y;
  for(last = n-1; last > 0; last--)
  {
    y = 0;
    for(x = 1; x <= last; x++)
    {
      if(b[x] > b[y])
      {
        swap(a, y, last);
        swap(b, y, last);
      }
      last--;
    }
  }

And

  static void sortByName(String[] a, double[] b,int n)
{
  int last, x, y;
  for(last = n-1; last > 0; last--)
    {
      y = 0;
      for(x = 1; x <= last; x++)
      {
        if(a[x].compareTo(a[y]) > 0)
        {
          swap(a, y, last);
          swap(b, y, last);
        }
        last--;
      }
    }
  

I tried to walkthrough these, and I think something is wrong with them. I don't think they fully sort my list, any help would be greatly appreciated.

[Campbell Ritchie]

What sort algorithm are you using?

[Amarnath Pandi]

Could you explain little more about the code.

in sortByPopulation,
You are comparing b[] but only swapping a and b. is it OK? In this case b[] values will not be changed right?
What is in a[] and b[]?