java_sort.java

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

public class Main {
	public static void main(String[] args) {
		List<Employee> employees = new ArrayList<>();
		employees.add(new Employee("hoge", 3));
		employees.add(new Employee("fuga", 1));
		employees.add(new Employee("piyo", 4));
		employees.add(new Employee("foo", 6));
		employees.add(new Employee("bar", 5));
		employees.add(new Employee("baz", 2));
		
		Collections.sort(employees, new Comparator<Employee>() {
			@Override
			public int compare(Employee e1, Employee e2) {
				return e1.number < e2.number ? -1 : 1;
			}
		});
		
		System.out.println(employees);
	}
}

class Employee {
	public final String name;
	public final Integer number;
	
	public Employee(String name, Integer number) {
		this.name = name;
		this.number = number;
	}

	@Override
	public String toString() {
		return "number: " + number + ", name: " + name;
	}
}