Java Custom ArrayList Object Sorting

Question

I have a problem with sorting an ArrayList of my own objects.

My class of these objects looks like that:

public class Robal {
 int[] gen = new int[5];
 int fit;
 Random losuj = new Random();
 public Robal(int przelacz) {
 for (int i=0; i<5; i++ ) {
 gen[i]=losuj.nextInt(2);
 }
 fit=dopasuj(gen, przelacz); 
 }
 int dopasuj(int[] gen, int przelacz) {
 int toDec=(gen[0]*1)+(gen[1]*2)+(gen[2]*4)+(gen[3]*8)+(gen[4]*16);
 return y(toDec, przelacz);
 }
 int y(int toDec, int przelacz) {
 if (przelacz == 1) {
 return toDec*toDec;
 } else if (przelacz == 2) {
 return 1;
 } else if(przelacz == 3) {
 return 1;
 } else if(przelacz == 4) {
 return 1;
 } else {
 return 1;
 }
 }
 void drukuj(int i) {
 System.out.println("Geny Robala "+i+": "+gen[0]+" "+gen[1]+" "+gen[2]+" "+gen[3]+" "+gen[4]+"\tfit:"+fit);
 }
}

and My Main class is:

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
public class PE {
public static void main (String[] args){
ArrayList<Robal> Robale = new ArrayList<Robal>();
int i=0;
while(i!=5){
Robale.add(new Robal(1));
i++;
}
Robale.get(0).drukuj(1);
Robale.get(1).drukuj(2);
Robale.get(2).drukuj(3);
Robale.get(3).drukuj(4);
Collections.sort(Robale, new Comparator<Robal>() {
public int compare(Robal a, Robal b){
return a.fit - b.fit;
}
});
Robale.get(0).drukuj(1);
Robale.get(1).drukuj(2);
Robale.get(2).drukuj(3);
Robale.get(3).drukuj(4);
}
}

but most of the time the Data before and after sorting is not the same... example result:

Geny Robala 1: 0 1 1 0 0 fit:36
Geny Robala 2: 1 0 1 0 1 fit:441
Geny Robala 3: 1 1 0 0 1 fit:361
Geny Robala 4: 0 1 1 1 0 fit:196
Geny Robala 1: 0 1 1 0 0 fit:36
Geny Robala 2: 0 0 0 1 0 fit:64
Geny Robala 3: 0 1 1 1 0 fit:196
Geny Robala 4: 1 1 0 0 1 fit:361

• Ted Hopp: How are you comparing the data?
• Roger Lindsjö: Which Data are talking about? Are the objects within the array modified?
• Adrian Modliszewski: No the data is not modified in any way...
• Ernest Friedman-Hill: Assuming the second four lines is the result of sorting the objects shown in the first four lines, the values of "fit" are in order, and the list of numbers associated with each value of "fit" don't change before and after. So what's the problem? Looks fine to me.
• John Glassmyer: How did you go from having a 1 0 1 0 1 fit:441 to having a 0 0 0 1 0 fit:64?

Answer 1

Are you sure you are not instantiating new Robal while sorting the list? that would cause the random values to shift

• Adrian Modliszewski: Ok problem found... here: while(i!=5){ wrong number... I had 5 instances of Robal...

Answer 2

You are adding 5 items to the array and printing only 4 before and after sorting. It seems that 5th item in unsorted list made it to the top 4. Can you print one more item and see if things look good?