排序列表 - 字符串元素

Question

I have an object list like this:

List <myObjectModel> list = new ArrayList ();

myObjectModel is composed of two strings (name and placement)

In this list there are the following elements in this order:

myObjectModel ("jeans", "B2")

myObjectModel ("jonnhy", "A1")

myObjectModel ("amanda", "H12")

myObjectModel ("samy", "A2")

myObjectModel ("bertrand", "G6")

I would like to sort my list on the second string (A1 jonnhy, A2 samy, B2 jean, G6 bertrand, H12 amanda)

Is it possible with "sort"?

Thank you

Answer 1

Using sort method of List:

 myObjectModelList.sort(Comparator.comparing(MyObjectModel::getProperty2));

Using Java 8 stream API:

List<MyObjectModel > myObjectModelList = list.stream()
                  .sorted(Comparator.comparing(MyObjectModel::getProperty2))
                  .collect(Collectors.toList());

Answer 2

if you are talking about retrieving the list sorted from the database then use @OrderBy

like this

@OrderBy("second_string ASC")
List <myObjectModel> list = new ArrayList ();

and second_string here is the column name in the table

Answer 3

You can use JAVA Stream API to solve this problem. But i think it is not efficient. I suggest Comparator method. I write codes as below,

Main Method

 public static void main(String[] args) { List <myObjectModel> list = new ArrayList<> (); list.add(new myObjectModel ("jeans", "B2")); list.add(new myObjectModel ("jonnhy", "A1")); list.add(new myObjectModel ("amanda", "H12")); list.add(new myObjectModel ("samy", "A2")); list.add(new myObjectModel ("bertrand", "G6")); list.sort(new myObjectComparator()); System.out.println(list); }

Java Model Class

 public class myObjectModel{ public String name; public String placement; public myObjectModel(String name, String placement){ this.name = name; this.placement = placement; } @Override public String toString() { return this.name+", "+this.placement; } }

Comparator Class

 import java.util.Comparator; public class myObjectComparator implements Comparator<myObjectModel>{ @Override public int compare(myObjectModel o1, myObjectModel o2) { return o1.placement.compareTo(o2.placement); } }