Having trouble on 2nd TODO comment public static HashSet doH

Having trouble on 2nd //TODO comment.

public static HashSet<Integer> doHashSetRemoveFromSmallest(int numItems) {

       System.out.print(\"doHashSetRemoveFromSmallest: \");
       HashSet<Integer> set = new HashSet<>();

       // TODO Write code that adds integers 0 through (numitems - 1)
       // to set.

       for(int i=0; i<=numItems-1; i++){
           set.add(i);
       }
      
       long startTime = getTimestamp();

       // TODO Write code that removes the smallest element from set,
       // repeatedly until the set is empty.

      
      
       long endTime = getTimestamp();
       long totalTime = endTime - startTime;
       System.out.println(totalTime);
      
       return set;
   }

Solution

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package chegg;

import java.util.Collections;
import java.util.HashSet;

public class Program {

  
public static HashSet<Integer> doHashSetRemoveFromSmallest(int numItems) {
System.out.print(\"doHashSetRemoveFromSmallest: \");
HashSet<Integer> set = new HashSet<>();
// TODO Write code that adds integers 0 through (numitems - 1)
// to set.
for(int i=0; i<=numItems-1; i++){
set.add(i);
}

Integer min;
long startTime = System.currentTimeMillis();
// TODO Write code that removes the smallest element from set,
// repeatedly until the set is empty.
while(!set.isEmpty())
{
min = Collections.min(set);
set.remove(min);
System.out.println(\"Removing \"+min+\" from set\");
}

long endTime = System.currentTimeMillis();
long totalTime = endTime - startTime;
System.out.println(totalTime);

return set;
}

public static void main(String[] args)
{
HashSet<Integer> s;

s = doHashSetRemoveFromSmallest(5);
  
//Should be zero since we will be removing all the min elements till the size of set become zero
System.out.println(\"Size of set is : \"+s.size());
}
}

run:
doHashSetRemoveFromSmallest: Removing 0 from set
Removing 1 from set
Removing 2 from set
Removing 3 from set
Removing 4 from set
4
Size of set is : 0
BUILD SUCCESSFUL (total time: 1 second)