champ.exe :
I have a list of Cars scheduled for delivery for multiple dates which needs to be sorted on the basis of the below points:
- If
isReady>0,
then it should be displayed first in the table. And then the other values come below it for that particular date. - If
isReady>0
and Objectgear!=null
then, it is displayed first in the table for that particular date. Followed by the other values where Objectgear==null
. - If
isReady>0
, Objectgear!=null
and Objecttyre!=null
, then that value is displayed first in the table for that particular date. Followed by the other values where Objectgear==null
andtyre==null
.
Here are the class
codes:
public class Car {
private int isReady;
private Tyre tyre;
private Gear gear;
private Date deliveryDate;
}
public class Gear {
private int id;
private String type;
}
public class Tyre {
private int id;
private String grip;
}
public class CarComparator implements Comparator<Car> {
@Override
public int compare(Car entry1, Car entry2) {
int value = 0;
if (entry1.getIsReady() > entry2.getIsReady()) {
value = -1;
} else if (entry1.getIsReady() < entry2.getIsReady()) {
value = 1;
} else if (entry1.getIsReady() == entry2.getIsReady()) {
value = 0;
}
return value;
}
}
I have developed a Comparator which works fine for the first condition where
isReady>0
. Could you please help me with the other conditions mentioned above.
Thanks in advance.
Ioannis Barakos :
Check this comparator so you can sort with multiple attributes
public class CarComparator implements Comparator<Car> {
@Override
public int compare(Car entry1, Car entry2) {
int value;
if (entry1.getDeliveryDate().before(entry2.getDeliveryDate())){
value = -1;
}else if (entry1.getDeliveryDate().equals(entry2.getDeliveryDate())){
value = 0;
}else{
value =1;
}
//For same day
if (value==0){
if (entry1.getIsReady() > entry2.getIsReady()) {
value = -1;
} else if (entry1.getIsReady() < entry2.getIsReady()) {
value = 1;
} else if (entry1.getIsReady() == entry2.getIsReady()) {
value = 0;
}
}
//if same isReady
if (value==0){
if (entry1.getGear()!=null && entry2.getGear()==null) {
value = -1;
} else if (entry1.getGear()==null && entry2.getGear()==null) {
value = 0;
} else{
value = 1;
}
}
//if still equals
if (value==0){
if (entry1.getTyre()!=null && entry2.getTyre()==null) {
value = -1;
} else if (entry1.getTyre()==null && entry2.getTyre()==null) {
value = 0;
} else{
value = 1;
}
}
return value;
}
}
I am not sure if this is what you try to do. What the above comparator does is: First to sort with Dates, if it finds equal dates (value=0), it compares the isReady, then getGear() and finally the getTyre().
That way you can add as many attributes as you need in your comparator.
Including the main method with 3 cars
public class Main {
public static void main (String[]args) throws UnsupportedEncodingException, ParseException {
List<Car> carL = new ArrayList<Car>();
Car car1 = new Car();
car1.setDeliveryDate(new Date());
Gear gear1 = new Gear();
car1.setGear(gear1);
Tyre tyre1 = new Tyre();
car1.setTyre(null);
car1.setId(1);
car1.setDeliveryDate((new SimpleDateFormat("dd-MM-yyyy")).parse("01-01-2000"));
car1.setIsReady(0);
Car car2 = new Car();
car2.setDeliveryDate(new Date());
Gear gear2 = new Gear();
car2.setGear(gear2);
Tyre tyre2 = new Tyre();
car2.setTyre(tyre2);
car2.setId(2);
car2.setDeliveryDate((new SimpleDateFormat("dd-MM-yyyy")).parse("02-01-2000"));
car2.setIsReady(1);
Car car3 = new Car();
car3.setDeliveryDate(new Date());
Gear gear3 = new Gear();
car3.setGear(gear3);
Tyre tyre3 = new Tyre();
car3.setTyre(tyre3);
car3.setId(3);
car3.setDeliveryDate((new SimpleDateFormat("dd-MM-yyyy")).parse("01-01-2000"));
car3.setIsReady(1);
carL.add(car1);
carL.add(car2);
carL.add(car3);
Collections.sort(carL, new CarComparator());
for (Car car : carL) {
System.out.println("car: " + car.toString());
}
}
}
outputs:
car: Car{id=3, isReady=1, tyre=false, gear=false, deliveryDate=Sat Jan 01 00:00:00 EET 2000}
car: Car{id=1, isReady=0, tyre=true, gear=false, deliveryDate=Sat Jan 01 00:00:00 EET 2000}
car: Car{id=2, isReady=1, tyre=false, gear=false, deliveryDate=Sun Jan 02 00:00:00 EET 2000}
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