Sorting

Main.java

import java.util.*;

public class Main {

    public static class Foo implements Comparable<Foo> {

        private final int value;

        public Foo(int value) {
            this.value = value;
        }

        @Override
        public int compareTo(Foo foo) {
            return value - foo.value;
        }

        @Override
        public String toString() {
            return "Foo(" + value + ")";
        }
    }

    public static void main(String[] args) {
        Comparator<Foo> comp = (foo1, foo2) -> {
        Comparator<Foo> comp = (foo1, foo2) -> {
            if (foo1 == null && foo2 == null) return 0;
            if (foo1 == null)                 return -1;
            if (foo2 == null)                 return 1;
            return foo1.compareTo(foo2);
        };
        List<Foo> foos = new ArrayList<>();
        foos.add(null);
        for (int i = 0; i < 10; i++) {
            foos.add(new Foo(i));
        }
        foos.add(null);
        foos.add(null);
        foos.add(3, null);
        foos.add(10, null);
        foos.sort(comp);
        System.out.println(foos);
    }
}