如：

package bolg;

public class Person implements Comparable{

    String name;
    int age;

    Person(String name,int age)
    {
        this.name=name;
        this.age=age;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }

    @Override
    public int compareTo(Object o) {
        // TODO Auto-generated method stub
        int i = 0;
        i=name.compareTo(((Person)o).name);

        if(0==i)
        {
            return age-((Person)o).age;

        }
        else {
            return i;
        }
    }

}

Test

package bolg;

import java.util.Arrays;

public class TestPerson {


    public static void   main(String args[])
    {
     Person[] persons = new Person[] { new Person("a", 30), new Person("ab", 20) };
        Arrays.sort(persons);
        for (int i = 0; i < persons.length; i++) {
            Person user = persons[i];
          System.out.println(user.getName() + " " + user.getAge());
        }
    }
}

输出结果

a 30
ab 20

-Comparator接口

public interface Comparator<T> {  
   int compare(T o1, T o2);  
   boolean equals(Object obj);  
} 

    为什么可以不实现 equals(Object obj) 函数呢？ 因为任何类，默认都是已经实现了equals(Object obj)的。 Java中的一切类都是继承于java.lang.Object，在Object.java中实现了equals(Object obj)函数；所以，其它所有的类也相当于都实现了该函数。

package bolg;

import java.util.Comparator;

public class PersonComparator implements Comparator{

    @Override
    public int compare(Object o1, Object o2) {
        // TODO Auto-generated method stub      
        return ((Person) o1).getAge() - ((Person) o2).getAge();

    }
}

package bolg;

import java.util.Arrays;

public class TestPerson {


    public static void   main(String args[])
    {
     Person[] persons = new Person[] { new Person("a", 30), new Person("ab", 20) };
      //  Arrays.sort(persons);
    Arrays.sort(persons,new PersonComparator());
        for (int i = 0; i < persons.length; i++) {
            Person user = persons[i];
          System.out.println(user.getName() + " " + user.getAge());
        }
    }
}

ab 20
a 30