Bluasul Bluasul - 1 month ago 16
Java Question

Java- Sorting int array

I'm trying to use this method to sort an integer array in ascending order. But my for loop runs through it only once.

public void sortArray()
{
boolean sorted = false;

while(sorted == false)
{
int temp;
for(int i = 0; i < inArray.length - 1; i++)
{
if(inArray[i] > inArray[i + 1])
{
temp = inArray[i];
inArray[i] = inArray[i + 1];
anArray[i + 1] = temp;
}
}
sorted = true;
}
}


I know it has to do with how I'm handling that boolean flag, but I'm not sure how to go about fixing it. Any suggestions would be appreciated. Thanks in advance.

Answer

There are multiple issues here:

  1. while (sorted = false) sets sorted to false and then tests the resulting value false, meaning that you never enter the loop body at all (not once as per your question).

  2. If you fix that, your code will only run the while loop body once (thus leaving the array not sorted yet), because you have sorted = true as an unconditional statement at the end of the loop body.

You need to have a flag that assumes the array is sorted, and then is cleared if you find evidence it wasn't, something like:

public void sortArray()
{
   boolean sorted;

   do
   {
       sorted = true;  // Assume it's sorted
       int temp;
       for(int i = 0; i < inArray.length - 1; i++)
       {
          if(inArray[i] > inArray[i + 1])
          {
             temp = inArray[i];
             inArray[i] = inArray[i + 1];
             anArray[i + 1] = temp;
             sorted = false; // We changed something, so assume we need to do another pass
          }
       }
   }
   while (!sorted);
}

Side note: This is just a style thing, but it's generally best to scope variables as narrowly as possible. There's no need for temp to be outside the for loop or even outside the if block, move it inside the if block

public void sortArray()
{
   boolean sorted;

   do
   {
       sorted = true;  // Assume it's sorted
       for(int i = 0; i < inArray.length - 1; i++)
       {
          if(inArray[i] > inArray[i + 1])
          {
             int temp = inArray[i];
             inArray[i] = inArray[i + 1];
             anArray[i + 1] = temp;
             sorted = false; // We changed something, so assume we need to do another pass
          }
       }
   }
   while (!sorted);
}