基于条件的排序列表（升序或降序）

Question

我想根据两个属性对列表进行排序，但要满足一定的条件。下面的类有两个属性--memberid和membernumber。其值如下所示。

obj ()
{
   memberid;
   membernumber;
}

Values Assigned : 
obj1 = {1,15}
obj2 = {3,10}
obj3 = {2,20}
obj4 = {2,10}
obj5 = {3,15}
obj6 = {4,25}
obj7 = {2,50}

obj1 = {1,15}
obj7 = {2,50} >> As 2 are multiple sort on membernumber as highest being 50
obj3 = {2,20}
obj4 = {2,10}
obj5 = {3,15}
obj2 = {3,10}
obj6 = {4,25}

public class sortId implements Comparator<obj > {

public int compare(obj o1, obj o2)
   {
     int id1 =  o1.getmemberId();
     int id2 =  o2.getmemberId();       
     return id1 - id2 ;     
    }
}

Answer 1

您可以使用collections.sort，要进行降序排序，您可以使用负数来反向排序，如下所示：

List<obj> list = Arrays.asList(new obj(1, 15), new obj(3, 10), new obj(2, 20),
        new obj(2, 10), new obj(3, 25), new obj(2, 50));

Collections.sort(list, new Comparator<obj>() {
    @Override
    public int compare(obj o1, obj o2) {
        if (o1.getMemberid() != o2.getMemberid()) {
            return o1.getMemberid() - o2.getMemberid();
        } else {
            //for the second sort you can use negative to sort descending
            return -(o1.getMembernumber() - o2.getMembernumber());
            //     ^-------------------------------------------------------
        }
    }
});

产出

[{1,15}, {2,50}, {2,20}, {2,10}, {3,25}, {3,10}]