landor — Tue, 07 Apr 2009 08:40:00 GMT

用Collections.sort�Ҏ��对list排序有两�U�方�?br /> �W�一�U�是list中的对象实现Comparable接口�Q�如下：

/**
* �Ҏ��order对User排序
*/
public class User implements Comparable<User>{
    private String name;
    private Integer order;
    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;
    }
    public int compareTo(User arg0) {
        return this.getOrder().compareTo(arg0.getOrder());
    }
}

��试一下：

public class Test{

    public static void main(String[] args) {
        User user1 = new User();
        user1.setName("a");
        user1.setOrder(1);
        User user2 = new User();
        user2.setName("b");
        user2.setOrder(2);
        List<User> list = new ArrayList<User>();
        //此处add user2再add user1
        list.add(user2);
        list.add(user1);
        Collections.sort(list);
        for(User u : list){
            System.out.println(u.getName());
        }
    }
}

输出�l�果如下
a
b
�W�二�U�方法是�Ҏ��Collections.sort重蝲�Ҏ��来实玎ͼ�例如�Q?br />

/**
* �Ҏ��order对User排序
*/
public class User { //此处无需实现Comparable接口
    private String name;
    private Integer order;
    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;
    }
}

�ȝ��中这样写卛_��Q?br />

public class Test{
    public static void main(String[] args) {
        User user1 = new User();
        user1.setName("a");
        user1.setOrder(1);
        User user2 = new User();
        user2.setName("b");
        user2.setOrder(2);
        List<User> list = new ArrayList<User>();
        list.add(user2);
        list.add(user1);

        Collections.sort(list,new Comparator<User>(){
            public int compare(User arg0, User arg1) {
                return arg0.getOrder().compareTo(arg1.getOrder());
            }
        });
        for(User u : list){
            System.out.println(u.getName());
        }
    }
}

输出�l�果如下
a
b
前者代码结构简单，但是只能�Ҏ��固定的属性排序，后者灵�z�，可以临时指定排序��，但是代码不够��z?br />
择优用之�?

landor 2009-04-07 16:40 发表评论

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