How to solve sorting of different balls by collection

Question

Suppose I have one container that contain different colors of ballons

such as Red, Blue, Green, Red,Blue,Red, Blue, Green in this order,
now sort that baloon in such manner so Red baloon will be added first
then Blue baloon and last is Green balloons. Use the proper collection

Use a `List`. Call `List#sort(Comparator)`. Pass a `Comparator` that defines the ordering you described. If you already have some code, but you're having a _specific_ problem, then please demonstrate that problem with a [mre]. — Slaw, Sep 25 '22 at 05:37

Abra · Answer 1 · 2022-09-25T06:26:25.767

Just make your colors an enum.

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class Balloons {
    enum Colors {RED, BLUE, GREEN}

    public static void main(String[] args) {
        List<Colors> list = new ArrayList<>();
        list.add(Colors.RED);
        list.add(Colors.BLUE);
        list.add(Colors.GREEN);
        list.add(Colors.RED);
        list.add(Colors.BLUE);
        list.add(Colors.RED);
        list.add(Colors.BLUE);
        list.add(Colors.GREEN);
        Collections.sort(list);
        System.out.println(list);
    }
}

Running above code outputs the following:

[RED, RED, RED, BLUE, BLUE, BLUE, GREEN, GREEN]

Alternatively, if your colors are strings, define an appropriate comparator.

import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;

public class Balloons {

    public static void main(String[] args) {
        List<String> list = new ArrayList<>();
        list.add("Red");
        list.add("Blue");
        list.add("Green");
        list.add("Red");
        list.add("Blue");
        list.add("Red");
        list.add("Blue");
        list.add("Green");
        Comparator<String> c = (s1, s2) -> {
            if ("Red".equals(s1)) {
                if ("Red".equals(s2)) {
                    return 0;
                }
                return -1;
            }
            else if ("Blue".equals(s1)) {
                if ("Red".equals(s2)) {
                    return 1;
                }
                else if ("Blue".equals(s2)) {
                    return 0;
                }
                return -1;
            }
            else {
                if ("Green".equals(s2)) {
                    return 0;
                }
                return 1;
            }
        };
        list.sort(c);
        System.out.println(list);
    }
}

How to solve sorting of different balls by collection

1 Answers1