How would I alter my code?

**miss confused** · July 18th, 2010, 11:38 PM

If my code:

public void sortArray () {
int beginP = 0;
int endP = myArray.length-1;
while(beginP<endP){
  if((myArray[beginP]!=GREEN) && (myArray[endP]!=BLUE)){
    swap(beginP, endP);
  }
  while((beginP < myArray.length) && (myArray[beginP]==GREEN)){
    beginP++;
  }
  while(myArray[endP]==BLUE){
    endP--;
  }
}

produced: G G G B B B B

how would I alter it so that it would produce: B B B B G G G?

I feel as though I am missing one step, but I cannot put my finger on it.

**bbr201** · July 19th, 2010, 01:08 AM

Alter it how? Why can't you just use the same sorting algorithm and change every BLUE with a GREEN and vice versa?

**miss confused** · July 19th, 2010, 06:03 AM

I tried that before, I don't know why that didn't work.

**Norm** · July 19th, 2010, 07:28 AM

Have you tried debugging the code by adding some println()s to show what is happening?

**helloworld922** · July 19th, 2010, 09:29 AM

I would recommend implementing a compareTo() method that determines which color comes before which.

Something like:

/**
 * Blue comes before green.
 *
 * Returns less than 0 if item1 comes before item2
 * Returns 0 if item1 comes at the same place as item2
 * Returns greater than 0 if item1 comes after item2
 */
public static int compareTo(ColorItem item1, ColorItem item2)
{
    int val1 = 0;
    int val2 = 0;
    if(item1 == BLUE)
    {
        val1 = 1;
    }
    else
    {
        val1 = 2;
    }
 
    if(item2 == BLUE)
    {
        val2 = 1;
    }
    else
    {
        val2 = 2;
    }
 
    return val1 - val2;
}

Then, somewhere in your code implement a standard sorting algorithm (say, selection sort because it's very easy).

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