Question

My question is about how to sort an ArrayList with custom Object by one of them properties but starting from a custom condition.

Let me explain better, here is my code:

public static void sortArrayListByProperty(ArrayList colorList){

        Collections.sort(colorList, new Comparator(){

            public int compare(Object emp1, Object emp2){

                int intValue1 = ((ColorCounter)emp1).getIntColorValue();        
                int intValue2 = ((ColorCounter)emp2).getIntColorValue();

                if(intValue1 < intValue2)
                    return 1;
                else if(intValue1 > intValue2)
                    return -1;
                else
                    return 0;    
            }
        });
    }

This will sort my ArrayList from bigger to smaller.

But what I want is to sort my ArrayList from a starting number that I will specify.

For example if ArrayList contains

5 3 9 1 14 

lets say that I want numbers start from 3 then I need to have

3 5 9 14 1

I hope is clear enought…

Is it possible?

@Joachim Sauer

Thank you, I edited your code a little and changed return values and it worked!

Edited code:

if (cv1 >= threshold && cv2 < threshold) {
   return -1;
} else if (cv2 >= threshold && cv2 < threshold) {
   return -1;
} else if (cv1 < cv2) {
   return 1;
} else if (cv1 > cv2) {
   return 1;
} else {
   return 0;    
}

Test example:

16777215
16448250
15790320
4013373

Sorting by 15790320:

15790320
16448250
16777215
4013373

Answer 1

You could try this:

public class ColorCounterComparator implements Comparator<ColorCounter> {
  private final threshold;

  public ColorCounterComparator(final int threshold) {
    this.threshold = threshold;
  }

  @Override
  public int compare (ColorCounter c1, ColorCounter c2) {
    int cv1 = c1.getIntColorValue();
    int cv2 = c1.getIntColorValue();

    if (cv1 >= threshold && cv2 < threshold) {
       return -1;
    } else if (cv2 >= threshold && cv2 < threshold) {
       return 1;
    } else if (cv1 < cv2) {
       return -1;
    } else if (cv1 > cv2) {
       return 1;
    } else {
       return 0;    
    }
  }
}

This is obviously very untested, might have some off-by-one-errors and might have flipped the -1/1 values. But it should show you the basic idea 😉