Can Java garbage collector randomly delete objects in the On-Heap tier?

c = null;//going to gc.

private static List<WeakReference<Car>> cars = new ArrayList<WeakReference<Car>>();

public static synchronized Car createCar(int id) {
   WeakReference<Car> result= new WeakReference<Car>(new Car(id));
   int index= cars.indexOf(result);
   if (index==-1){
      cars.add(result);
      return result.get();
   } else {
      return cars.get(index).get();
   }
}

-XX:+UseCMSInitiatingOccupancyOnly -XX:CMSInitiatingOccupancyFraction=N

[int] $i
#{
$i = New-Object int;
$i = 20;
#}
Write-Host "i is $i"

for( [long] $j = 4000; $j -le 5000; $j++ )
{
    $newVar = New-Variable "aNewObject$j" 
    $newVar = $j;  
}

if($i -eq $null)
{
    Write-Host "I is destroyed"
}

$newVar = New-Variable "aNewObject$j"