list排序问题

[bluemouse_2008]

查询结果的list里面放了一系列的对象，对象里面有属性，现在要求将list查询出来后
就根据对象的某个属性排序（如对象的年龄降序排），list有这样的排序方法吗？求
解决方法

[mythling]

有啊。呵呵

[mythling]

departmentList = departmentService.findAll();
		Collections.sort(departmentList, new CompartorDepartment());

public class CompartorDepartment extends Department implements Comparator
{
	private static final long serialVersionUID = 1L;

	public CompartorDepartment()
	{

	}

	public int compare(Object a, Object b)
	{
		Department s1 = (Department) a;
		Department s2 = (Department) b;
		return s1.getId() - s2.getId() < 0 ? -1 : 1;

	}
}

[骑着狼看狮子丶]

http://www.blogjava.net/zygcs/archive/2008/01/17/176032.html

[woainiyibangcui]

用SortedSet吧 bean实现一下Comparator接口就行了 想怎么排怎么排

[孤独剑客]

[Quote=引用 3 楼 wy100304441 的回复:]
http://www.blogjava.net/zygcs/archive/2008/01/17/176032.html
[/Quote]

这个很好!

[宁波朱超]

[Quote=引用楼主 bluemouse_2008 的回复:]
查询结果的list里面放了一系列的对象，对象里面有属性，现在要求将list查询出来后
就根据对象的某个属性排序（如对象的年龄降序排），list有这样的排序方法吗？求
解决方法
[/Quote]

請用 COLLECTIONS

[closewbq]

		 Collections.sort(list, new Comparator<对象>(){
			 public int compare(对象 o1, 对象 o2)
			    {
			        return o1.getAge()>o2.getAge()?1 :(o1.getAge()<o2.getAge()?-1:0);
			    }
		 });

[blazingfire]

示例按birthday属性排序

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Date;
import java.util.List;

public class Test {

    public static class Man {

        private String birthday;
        private String name;

        public Man() {
        }

        public Man(String name, String birthday) {
            this.name = name;
            this.birthday = birthday;
        }

        @Override
        public String toString() {
            return name + "  " + birthday;
        }

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

        public String getBirthday() {
            return birthday;
        }

        public void setBirthday(String birthday) {
            this.birthday = birthday;
        }
    }

    public static void main(String[] args) {
        List<Man> list = new ArrayList<Man>();
        list.add(new Man("张三", "2000-01-01 20：20：20"));
        list.add(new Man("李四", "2001-01-01 20：20：20"));
        list.add(new Man("王五", "2005-05-01 20：20：20"));
        list.add(new Man("BBB", "2003-01-01 20：20：20"));

        System.out.println("排序前：" + list);
        Collections.sort(list, new Comparator<Man>() {

            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd hh：mm：ss");

            private Date getBirthday(Man m) {
                if (m == null || m.getBirthday() == null)
                    return null;
                try {
                    return sdf.parse(m.getBirthday());
                } catch (ParseException e) {
                    return null;
                }
            }

            public int compare(Man o1, Man o2) {
                Date d1 = getBirthday(o1);
                Date d2 = getBirthday(o2);
                if (d1 == null && d2 == null)
                    return 0;

                if (d1 == null)
                    return -1;
                if (d2 == null)
                    return 1;
                return d1.compareTo(d2);
            }

        });
        System.out.println("排序后：" + list);
    }

}

[mythling]

晕，还不是和我的实现一样，不看也罢！！！！

[bluemouse_2008]

3楼给的很详细，谢谢了！