java比较器

13shu

需求:现有一对象Person有2个属性name和age,把Person对象先按照name属性进行比较排序(字母),如name有相同的按照age的大小排序.
1.构造Person类
public class Person {private String name;private int age;public Person(String name, int age) {this.age = age;this.name = name;}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;}} 2.编写java比较器
public class Comparator implements java.util.Comparator {private int compare(String a, String b) {return a.compareTo(b);}private int compare(int a, int b) {return (a > b ? (a < b ? 0 : 1) : -1);}public int compare(Object o1, Object o2) {Person p1 = (Person) o1;Person p2 = (Person) o2;String name1 = p1.getName();String name2 = p2.getName();int age1 = p1.getAge();int age2 = p2.getAge();return (compare(name1, name2) == 0 ? compare(age1, age2) : compare(name1, name2));}}  
3.测试代码
public static void main(String[] args) {Person p1 = new Person("a", 4);Person p2 = new Person("b", 2);Person p3 = new Person("c", 1);Person p4 = new Person("a", 1);Person p5 = new Person("a", 6);Person p6 = new Person("a", -1);TreeMap tm = new TreeMap(new Comparator());tm.put(p1, "");tm.put(p2, "");tm.put(p3, "");tm.put(p4, "");tm.put(p5, "");tm.put(p6, "");for (Iterator it = tm.keySet().iterator(); it.hasNext();) {Person key = (Person) it.next();System.out.println(key.getName()+" "+key.getAge());}}