Java List 排序问题
两种方法:
第一种方法,就是list中对象实现Comparable接口,代码如下:
public class Person implements Comparable<Person> { private String name; private Integer order; /** * @return the name */ public String getName() { return name; } /** * @param name * the name to set */ public void setName(String name) { this.name = name; } /** * @return the order */ public Integer getOrder() { return order; } /** * @param order * the order to set */ public void setOrder(Integer order) { this.order = order; } @Override public int compareTo(Person arg0) { return this.getOrder().compareTo(arg0.getOrder()); } }
public static void main(String[] args) { List<Person> listA = new ArrayList<Person>(); Person p1 = new Person(); Person p2 = new Person(); Person p3 = new Person(); p1.setName("name1"); p1.setOrder(1); p2.setName("name2"); p2.setOrder(2); p3.setName("name3"); p3.setOrder(3); listA.add(p2); listA.add(p1); listA.add(p3); Collections.sort(listA); for (Person p : listA) { System.out.println(p.getName()); } }
第二种方法,就是在重载Collections.sort方法,代码如下:
public class Person { private String name; private Integer order; /** * @return the name */ public String getName() { return name; } /** * @param name * the name to set */ public void setName(String name) { this.name = name; } /** * @return the order */ public Integer getOrder() { return order; } /** * @param order * the order to set */ public void setOrder(Integer order) { this.order = order; } }
public static void main(String[] args) { List<Person> listA = new ArrayList<Person>(); Person p1 = new Person(); Person p2 = new Person(); Person p3 = new Person(); p1.setName("name1"); p1.setOrder(1); p2.setName("name2"); p2.setOrder(2); p3.setName("name3"); p3.setOrder(3); listA.add(p2); listA.add(p1); listA.add(p3); Collections.sort(listA, new Comparator<Person>() { public int compare(Person arg0, Person arg1) { return arg0.getOrder().compareTo(arg1.getOrder()); } }); for (Person p : listA) { System.out.println(p.getName()); } }
两次执行的结果都是:
name1
name2
name3