Question

样品清单

ArrayList<MyObject> list = new ArrayList<MyObject>();

list.add(new MyObject (1, "2011-04-27T09:40:01.607")); 
list.add(new MyObject (1, "2011-05-27T09:42:01.607"));
list.add(new MyObject (2, "2011-06-27T09:42:01.607"));
list.add(new MyObject (5, "2011-07-27T09:43:01.607"));
list.add(new MyObject (6, "2011-08-27T09:44:01.607"));
list.add(new MyObject (6, "2011-09-27T09:45:01.607"));
list.add(new MyObject (1, "2011-10-27T09:46:01.607"));

1：-如何根据ID对ArrayList进行排序

必需的输出

list.get(0)= (1, "2011-04-27T09:40:01.607")); 
list.get(1)=(1, "2011-05-27T09:42:01.607"));
list.get(2)= (1, "2011-10-27T09:46:01.607"));
list.get(3)=(2, "2011-06-27T09:42:01.607"));
list.get(4)=(5, "2011-07-27T09:43:01.607"));
list.get(5)=(6, "2011-08-27T09:44:01.607"));
list.get(6)=(6, "2011-09-27T09:45:01.607"));

2：-对ID进行排序时，然后根据ID的日期对每组ID进行排序

意味着ID（1）存在3次，因此ID（1）根据其日期排序

必填输出

list.get(0)= (1, "2011-10-27T09:46:01.607"));
list.get(1)=(1, "2011-05-27T09:46:01.607"));
list.get(2)= (1, "2011-04-27T09:46:01.607")); 
list.get(3)=(2, "2011-06-27T09:46:01.607"));
list.get(4)=(5, "2011-07-27T09:46:01.607"));
list.get(5)=(6, "2011-08-27T09:46:01.607"));
list.get(6)=(6, "2011-09-27T09:46:01.607"));

Answer 1

您可以有2个比较器，如下所示

IdSorter.java

public class IdSorter implements Comparator<MyObject> 
    {
        public int compare(MyObject o1, MyObject o2) 
        {
            return o1.getId() - o2.getId();
        }
    }

DateSorter.java

public class DateSorter implements Comparator<MyObject> 
    {
        public int compare(MyObject o1, MyObject o2) 
        {
            return o1.getTime().compareTo(o2.getTime());
        }
    }

然后您可以按照以下顺序进行排序

Java 8

Collections.sort(list, new IdSorter()
               .thenComparing(new DateSorter()));

Java 8以下

MyObjectChainedComparator.java

public class MyObjectChainedComparator implements Comparator<MyObject> {

    private List<Comparator<MyObject>> listComparators;

    @SafeVarargs
    public MyObjectChainedComparator(Comparator<MyObject>... comparators) {
        this.listComparators = Arrays.asList(comparators);
    }

    @Override
    public int compare(MyObject o1, MyObject o2) {
        for (Comparator<MyObject> comparator : listComparators) {
            int result = comparator.compare(o1, o2);
            if (result != 0) {
                return result;
            }
        }
        return 0;
    }
}

像下面一样使用类MyObjectChainedComparator.java

Collections.sort(list, new MyObjectChainedComparator(
               new IdSorter(),
               new DateSorter()));

您的结果将如下所示

Id 1 Time 2011-04-27T09:40:01.607
Id 1 Time 2011-05-27T09:42:01.607
Id 1 Time 2011-10-27T09:46:01.605
Id 2 Time 2011- 06-27T09:42:01.607
Id 5 Time 2011-07-27T09:43:01.607
Id 6 Time 2011-08-27T09:44:01.607
Id 6 Time 2011-09-27T09:45:01.607

Answer 2

解决此问题的另一种方法也使用此逻辑

Collections.sort(list, new MyObjectChainedComparator());

上课

public class MyObjectChainedComparator implements Comparator<MyObject> {


@Override
public int compare(MyObject o1, MyObject o2) {
     int result=o1.getId()-o2.getId();
     if (result==0)
     result =o2.getDate().compareTo(o1.getDate());
     return result;


}
 }

Answer 3

您应创建see -n ' /PATTERN/!{$be;d}; 1h;1!H; :e; ${g;s,^$[\n]\+\n[\n]\+\n[\n]\+\n$.*$[\n]\+\n[\n]\+\n[\n]\+$,\1\2,;p} '接口的新类，例如SortList和implement，如下所示：

Comparator

然后，对列表进行排序

class SortList implements Comparator<MyObject> {
    @Override
    public int compare(MyObject o1, MyObject o2) {
        if (o1.id < o2.id) {// less than
            return -1;
        } else if (o1.id > o2.id) {// greater than
            return 1;
        } else {// equal
            // If it is equal then compare by name
            return o1.name.compareTo(o2.name);
        }
    }
}

结果是：

public void sort() {
    ArrayList<MyObject> list = new ArrayList();
    list.add(new MyObject(1, "abcd"));
    list.add(new MyObject(1, "a"));
    list.add(new MyObject(1, "abc"));
    list.add(new MyObject(1, "ab"));

    Collections.sort(list, new SortList());

    for (MyObject o : list) {
        System.out.println("id: " + o.id + ", name: " + o.name);
    }
}

请注意：您必须更改我的代码以比较id: 1, name: a id: 1, name: ab id: 1, name: abc id: 1, name: abcd而不是Date。我只是写了一个简单的示例，让您了解其工作原理。

具有优先级ID和日期时间的排序列表模型

3 个答案: