JAVA: get variable of object using tree map method

Question

Say I have an object called Car:

public class Car(){
  String model;
  String brand;
  Integer yearReleased;
  float price;
}

and create a treemap of cars called cars:

TreeMap<Integer, Car> cars = new TreeMap<Integer, Car>();

Is there a method wherein I can search up the model of a car in the treelist? Something like .getKey() but allows to search an object variable. I'm trying to create a search function wherein it has a parameter of the treemap and the model to be searched and returns the key.

public searchModel(TreeMap<Integer, Car> list, String model){
  return list.getKey(model);
}

No, you have to have separate map for that.

Antoniossss
– Antoniossss

2021-05-16 15:15:18 +00:00
Commented May 16, 2021 at 15:15 — Antoniossss
– Antoniossss, Commented May 16, 2021 at 15:15

Mureinik · Accepted Answer · 2021-05-16 15:18:06Z

1

If there's no relationship between the model and the Integer key of the map, you have no choice but to iterate over all its values:

public List<Car> searchModel(TreeMap<Integer, Car> map, String model){
  return map.values()
            .stream()
            .filter(c -> c.model.equals(model))
            .collect(Collectors.toList());
}

answered May 16, 2021 at 15:18

Mureinik

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3 Comments

rr11 Over a year ago

thanks for this, I was just wondering how to get the input to be a string or something readable. When I print the list using -Arrays.toString- it it gives me [project.Car@65b3120a] instead

Mureinik Over a year ago

@rr11 You need to override Car's toString() mehos

sprinter Over a year ago

OP asked to return the key rather than the value. That'd be entrySet().stream().filter(e -> e.getValue().model.equals(model)).map(e -> e.getKey()).toList()

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