一、通过实现Comparable接口,这种方式表明,类自身是可比较的,有了比较才能进行排序。最好提供一种标志,如一个整形的属性,或者字符串类型。
代码说明
package sort; public class User implements Comparable<User> { private String name; private Integer order; @Override public int compareTo(User o) { return this.getOrder().compareTo(o.getOrder()); } public String getName() { return name; } public void setName(String name) { this.name = name; } public Integer getOrder() { return order; } public void setOrder(Integer order) { this.order = order; } }
测试方法
public static void test0() { User user1 = new User(); user1.setName("汉文"); user1.setOrder(1); User user2 = new User(); user2.setName("彝文"); user2.setOrder(2); User user3 = new User(); user3.setName("藏文"); user3.setOrder(3); List<User> list = new ArrayList<User>(); list.add(user3); list.add(user1); list.add(user2); Collections.sort(list); foreach(list); }
package sort; import java.text.Collator; import java.util.Locale; public class Employee implements Comparable<Employee> { private String name; public static Collator collator = Collator.getInstance(Locale.CHINESE); public Employee(String name) { this.name = name; } @Override public int compareTo(Employee o) { return collator.compare(this.getName(), o.getName()); } public String getName() { return name; } public void setName(String name) { this.name = name; } }测试代码
public static void test3() { Employee e = new Employee("谢谢"); Employee e2 = new Employee("不客气"); List<Employee> list = Arrays.asList(e,e2); Collections.sort(list); for (Employee o : list) { System.out.println(o.getName()); } }
二、通过实现Comparator接口,实现更多的排序规则。Comparator接口是一个工具类接口,它的名字含义是比较器的意思,即表示,用作比较,它与原有类的逻辑没有关系,只是实现两个类的比较逻辑,从这方面来说,一个类有多个比较器,只要有业务需求就可以产生比较器,就可以产生多种排序算法。
代码实现
package sort; import java.text.Collator; import java.util.Comparator; import java.util.Locale; public class ChineseStringComparator implements Comparator<User> { public static Collator collator = Collator.getInstance(Locale.CHINESE); @Override public int compare(User o1, User o2) { int i = collator.compare(o1.getName(), o2.getName()); System.out.println("Compare To: " + i); return i; } }
public static void test2() { User user1 = new User(); user1.setName("你"); User user2 = new User(); user2.setName("爱"); User user3 = new User(); user3.setName("他"); List<User> list = new ArrayList<User>(); list.add(user1); list.add(user2); list.add(user3); Collections.sort(list, new ChinesePinyinStringComparator()); foreach(list); }实例化一个Locale环境里中的Collator 对象,产生比较。这种方式大部分的中文能比较出结果,有点Bug的地方就是多音字会出现问题,如藏文,汉文,彝文,这三个词组会有问题(可自行测试)
三、总结
Comparable接口是实现类的默认排序算法,一个类稳定成熟后其compareto方法几乎不会变,而Comparator接口则是一个类的扩展排序工具。