Collections排序

collections

@Test
    public void testSort() {
        List<String> list = new ArrayList<>();
        list.add("adcva");
        list.add("gfdsa");
        list.add("fdad");
        list.add("aaaaa");
        Collections.sort(list, new Comparator<String>() {
            @Override
            public int compare(String o1, String o2) {
                return o1.charAt(0) - o2.charAt(0);
            }
        });
        for (String s : list) {
            System.out.println(s);
        }
    }

结果

adcva
aaaaa
fdad
gfdsa

package com.hou.test1;
 
public class SortA implements Comparable<SortA> {
     
    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;
    }
 
    @Override
    public String toString() {
        return "name:" + name + "--order:" + order;
    }
 
    @Override
    public int compareTo(SortA a) {
//       return a.getOrder()-this.order; //升序
//      return this.order-a.getOrder(); //倒序
//      return this.order.compareTo(a.getOrder());//升序
        return a.getOrder().compareTo(this.order);//倒序
    }