如下程式碼：

import java.util.*;

class company implements Comparable {
	private String name;
	private String technology;
	private double marketValue;
	private double salary;
	private int city;

	public company(String name, String technology, double marketValue, double salary, int city) {
		super();
		this.name = name;
		this.technology = technology;
		this.marketValue = marketValue;
		this.salary = salary;
		this.city = city;
	}

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

	/**
	 * @param name
	 *            the name to set
	 */
	public void setName(String name) {
		this.name = name;
	}

	/**
	 * @return the technology
	 */
	public String getTechnology() {
		return technology;
	}

	/**
	 * @param technology
	 *            the technology to set
	 */
	public void setTechnology(String technology) {
		this.technology = technology;
	}

	/**
	 * @return the marketValue
	 */
	public double getMarketValue() {
		return marketValue;
	}

	/**
	 * @param marketValue
	 *            the marketValue to set
	 */
	public void setMarketValue(double marketValue) {
		this.marketValue = marketValue;
	}

	/**
	 * @return the salary
	 */
	public double getSalary() {
		return salary;
	}

	/**
	 * @param salary
	 *            the salary to set
	 */
	public void setSalary(double salary) {
		this.salary = salary;
	}

	/**
	 * @return the city
	 */
	public int getCity() {
		return city;
	}

	/**
	 * @param city
	 *            the city to set
	 */
	public void setCity(int city) {
		this.city = city;
	}

	@Override
	public int compareTo(Object o) {
		// TODO Auto-generated method stub
		company comp = (company) o;
		int result = comp.getSalary() > salary ? 1 : (comp.getSalary() == salary ? 0 : -1);
		return result;
	}

	public String toString() {
		return "\r\tnum:" + name + " name:" + name + "\r";
	}
}

public class 比較器 {
	public static void main(String[] args) {
		List<company> list = new ArrayList<company>(10);
		list.add(new company("xx", "11", 1, 12, 1));
		list.add(new company("yy", "11", 1, 13, 1));
		list.add(new company("zz", "11", 1, 12, 1));
		Collections.sort(list); // 內部比較器:要排序的物件實現Comparable介面,可以對自身進行比較
		System.out.println(Arrays.toString(list.toArray()));

	}

}