1.是list中的對(duì)象實(shí)現(xiàn)Comparable接口：

/**
* 根據(jù)order對(duì)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());
    }
}

2.根據(jù)Collections.sort重載方法來(lái)實(shí)現(xiàn)：

 Collections.sort(list,new Comparator<user>(){
            public int compare(User arg0, User arg1) {
                return arg0.getOrder().compareTo(arg1.getOrder());
            }
        });

3.使用compareTo的注意事項(xiàng)
這個(gè)是提供給Integer，int則不可以。