Insert in order

[Paul D Statham]

I'm trying to create a list of random numbers and have them inserted in order, heres the function which is supposed to do the task. It's not quite working however. Basically I have a temporary buffer that copies all numbers from the end of the list until it gets to the point where the number is greater than the input_item. As for inserting the item however, it loops through the current list until it finds the position it should be in. Once this is complete what I want to happen is to go from the position the input_item has been placed and put all the numbers in the temporary buffer back in the primary buffer.

public int insertInOrder(String input_item)
{ 
    int i,j,insertPos;
    if(current_size>0)
    {
       int conversion = Integer.parseInt(input_item);   
       for(i=current_size;i>conversion;i--)
           tmp[i+1]=data[i];
       for(j=0;j<=current_size+1;j++)
       {
          if(data[j] != null)
          {                                    
             if(Func.lessThan(input_item,data[j]))
             {                      
                data[j]=input_item;                      
                break;
             }
             else if(input_item.equals(data[j]))
             {
                data[j+1]=input_item;
                break;
             }                 
          }
          else
          {
            data[j]=input_item;
            break;
          }
  
      }
      current_size++;
    }
    else
    {   
       data[0] = input_item;     
       current_size++;
    }
    return current_size;
}

[Ernest Friedman-Hill]

Hi Paul,
Welcome to JavaRanch!
If you're doing this just to get the job done, then why not use the static java.util.Arrays.sort() functions to sort the complete array. It will likely be faster than anything else you will come up with.
If you're writing your own sort routine just to learn how to write sort routines, then an algorithms book like Sedgewick Volume 1 would be a big help. What you're trying to write is something like an "insertion sort," and it's not only hard to write but terribly slow for arrays of any size; there are better choices.

[Paul D Statham]

Well basically i've been given the following pseudo code which I have to expand upon.

insertInOrder(S){
   loop1: search from beginning of list, look for an item >= S
   loop2: shift remaining list to its right, start from the end of the list
   insert S
}

[fred rosenberger]

Originally posted by Paul D Statham:

Once this is complete what I want to happen is to go from the position the input_item has been placed...
<snip>
loop2: shift remaining list to its right, start from the end of the list

forgive me, but these seem to be at odds. according to your pseudo-code, you should start moving the elements from the END, not the middle.
If this is a class assignment, shouldn't you do it the way it's asked for? This may be a minor point, but when I was teaching Math, if the students didn't do something the way it was supposed to be done, I woudn't give them full credit.
I don't want to start an educational debate, but this should be considered.
f

[Pradeep bhatt]

for(i=current_size;i>conversion;i--)           tmp[i+1]=data[i];  

why are you doing this?

[Michael Dunn]

Here's something to play around with. Compare the two, you might spot a difference.

class ArrayInsertSort
{
  int randNum[] = new int[10];
  public ArrayInsertSort()
  {
    for(int i = 0; i < randNum.length; i++) randNum[i] = (int)(Math.random()*100);
    display();
    sort();
    System.out.println("===");
    display();
  }
  public void sort()
  {
    int temp[] = new int[randNum.length];
    temp[0] = randNum[0];
    boolean inserted;
    for(int i = 1; i < randNum.length; i++)
    {
      inserted = false;
      for(int ii = 0; ii < i; ii++)
      {
        if(randNum[i] < temp[ii])
        {
          for(int iii = i; iii > ii; iii--)
          {
            temp[iii] = temp[iii-1];
          }
          temp[ii] = randNum[i];
          inserted = true;
          break;
        }
      }
      if(!inserted) temp[i] = randNum[i];
    }
    for(int i = 0; i < randNum.length; i++) randNum[i] = temp[i];
  }
  public void display()
  {
    for(int i = 0; i < randNum.length; i++) System.out.println(randNum[i]);
  }
  public static void main(String args[])
  {
    new ArrayInsertSort();
  }
}