// customized Comparator, I want deceading order

// 1. Collections.reverseOrder()

PriorityQueue<Integer> pq = new PriorityQueue<>(Collections.reverseOrder());

//2. Top-level class

class MyComparator implements Comparator<Student> {

@Override

public int compare(Student s1, Student s2) {

...

}

}

Collections.sort(students, new MyComparator());

// 3. Static nested class

class Solution {

private static class MyComparator implements Comparator<Student> {

@Override

public int compare(Student s1, Student s2) {

...

}

}

}

// 4, Anonymous class

Collections.sort(students, new Comparator<Student> {

@Override

public int compare(Student s1, Student s2) {

...

}

});

// Lambda expressions

Collections.sort(students, (s1, s2) -> s1.getName().compareTo(s2.getName()));

Collections.sort(students, (s1, s2) -> {

if(s1.getAge() == s2.getAge()) {

return 0;

}

else {

return s1.getAge() < s2.getAge() ? -1 : 1;

}

});