how do I sort an array of objects alphabeticaclly by a specific field

Question

I have an array of objects which contain a number of fields. I have a class with the constructors, setters and getters. One of the fields is name. I want to sort alphabetically all the names in the array and list them. Can anyone be of help? This is in java.

Thanks

Maybe. In what language? What kinds of objects are we talking about? — Parthian Shot, Oct 11 '16 at 07:03
First off: What language are you coding in? Second: Post some code, with your attempt. This way we can help you. [How to ask questions](http://stackoverflow.com/help/how-to-ask) — Roy123, Oct 11 '16 at 07:03
In how many different languages and for how many possible kinds of arrays/objects would you like your answer…? — deceze, Oct 11 '16 at 07:05
And there are certainly plenty of questions in [tag:java] about sorting arrays which have already been answered. How about http://stackoverflow.com/questions/12449766/java-sorting-sort-an-array-of-objects-by-property-object-not-allowed-to-use-co ? — deceze, Oct 11 '16 at 08:26

vaultboy · Answer 1 · 2016-10-12T07:13:04.460

You can do so with the Comparable interface. Lets assume we have a Class Car, which can be of a certain brand (name in this example)

public class Car implements Comparable<Car> {


    private String name;
    private String color;   

    /**
     * Names
     */
    public enum Name {

        FIAT("fiat"), RENAULT("renault"), HONDA("honda");

        private final String name;      

        private Name(final String name) {
            this.name = name;
        }

        public String toString() {
            return this.name;
        }
    }

    /**
     * Colors
     */
    public enum Colors {

        BLUE("blue"), RED("red"), YELLOW("yellow");

        private final String color;     

        private Colors(final String color) {
            this.color = color;
        }

        public String toString() {
            return this.color;
        }
    }

    /**
     * Construct car with name and color
     * @param name
     * @param color
     */
    public Car(Name name, Colors color) {
        this.name = name.toString();
        this.color = color.toString();
    }

    /**
     * return name
     * @return
     */
    public String getName() {
        return this.name;
    }

    /**
     * compare to other car
     */
    @Override
    public int compareTo(Car car2) {
        return this.name.compareTo(car2.getName());
    }
}

And the main:

import java.util.Arrays;

public class Main {

    //private static List<Car> cars = new ArrayList<Car>();
    private static Car[] cars = new Car[3];

    /**
     * @param args
     */
    public static void main(String[] args) {

        System.out.println("Create cars in array");
        cars[0] = new Car(Car.Name.RENAULT, Car.Colors.YELLOW);
        cars[1] = new Car(Car.Name.HONDA, Car.Colors.BLUE);
        cars[2] = new Car(Car.Name.FIAT, Car.Colors.RED);

//      System.out.println("Create cars in arraylist");     
//      cars.add(new Car(Car.Name.RENAULT, Car.Colors.YELLOW));
//      cars.add(new Car(Car.Name.HONDA, Car.Colors.BLUE));
//      cars.add(new Car(Car.Name.FIAT, Car.Colors.RED));

        System.out.println("Print cars");
        for (Car car : cars) {
            System.out.println("Car name: "+car.getName());
        }

        // sort cars, see Car class
        Arrays.sort(cars);

        System.out.println("Print cars after sort");
        for (Car car : cars) {
            System.out.println("Car name: "+car.getName());
        }
    }
}

See the console for output.

I don't understand, my objects are stored in array: movies[] movieArr = new movies[0]; — Alex, Oct 11 '16 at 10:15

how do I sort an array of objects alphabeticaclly by a specific field

1 Answers1