-
Notifications
You must be signed in to change notification settings - Fork 1
/
comparator_example.java
78 lines (65 loc) · 2.14 KB
/
comparator_example.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
class Student{
int rollNo;
String name;
int age;
public Student(int rollNo, String name, int age) {
this.rollNo = rollNo;
this.name = name;
this.age = age;
}
@Override
public String toString() {
return "Student{" +
"rollNo=" + rollNo +
", name='" + name + '\'' +
", age=" + age +
'}';
}
}
// used to sort Student by age
class AgeComparator implements Comparator<Student>{
@Override
public int compare(Student t1, Student t2) {
// this by default create ascending order
return t1.age-t2.age;
// this by default create descending order
//return t2.age-t1.age;
}
}
// used to sort Student by name
class NameComparator implements Comparator<Student>{
@Override
public int compare(Student t1, Student t2) {
// this by default create ascending order
return t1.name.compareTo(t2.name);
// this by default create descending order
//return t2.name.compareTo(t1.name);
}
}
public class comparator_example {
public static void main(String[] args) {
List<Student> list=new ArrayList<>();
list.add(new Student(1,"Abc",22));
list.add(new Student(2,"Xyz",20));
list.add(new Student(3,"Loc",23));
System.out.println("### Sort by Age ###");
Collections.sort(list,new AgeComparator());
list.forEach(System.out::println);
System.out.println();
System.out.println("=================================");
System.out.println();
System.out.println("### Sort (reverse order) by Age ###");
Collections.sort(list,Collections.reverseOrder(new AgeComparator()));
list.forEach(System.out::println);
System.out.println();
System.out.println("=================================");
System.out.println();
System.out.println("### Sort by Name ###");
Collections.sort(list,new NameComparator());
list.forEach(System.out::println);
}
}