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package collections;

import java.util.ArrayList;

import java.util.Collections;

import java.util.Comparator;

import java.util.List;

//we can sort only List<T> with cCollections.sort()

class RevSortIntList implements Comparator<Integer> {

@Override

public int compare(Integer o1, Integer o2) {

return -o1.compareTo(o2);

}

}

// class PersonExtra extends Person{

// }

public class Sorting {

public static void main(String[] args) {

//Sorting a list of Strings

List<String> l1 = new ArrayList<>();

l1.add("Sandeep");l1.add("Bolla");l1.add("Sampath");

System.out.println(l1);

Collections.sort(l1);//sorting using natural ordering

System.out.println(l1);

Collections.sort(l1,new Comparator<String>() { //Sorting in reverseorder using anonymous classes

@Override

public int compare(String o1, String o2) {

return -o1.compareTo(o2);

}

});

System.out.println(l1);

//Sorting a list of integers

List<Integer> l2 = new ArrayList<>();

l2.add(5);l2.add(2);l2.add(7);l2.add(30);l2.add(5);

System.out.println(l2);

Collections.sort(l2);

System.out.println(l2);

Collections.sort(l2, new RevSortIntList());

System.out.println(l2);

//List<Integer> l6 = Collections.emptyList(); returns an empty list

//Sorting a list of Objects of a Custom class

List<Person> l3 = new ArrayList<>(); //Person class is in WidObjects.java

l3.add(new Person(1,"Sampath"));l3.add(new Person(5,"Sandeep"));l3.add(new Person(2,"Bolla"));

System.out.println(l3);

Collections.sort(l3,new Comparator<Person>() {

@Override

public int compare(Person o1, Person o2) { //sorting in ascending order based on the IDs

//return ((Integer)o1.getId()).compareTo(o2.getId());

if(o1.getId()<o2.getId()) return -1; //canbe implented using compareTo also as shown in aobve line

else return 1;

}

});

System.out.println(l3);

Collections.sort(l3,new Comparator<Person>() {

@Override

public int compare(Person o1, Person o2) { //sorting in ascending order based on the NAMEs

return (o1.getName()).compareTo(o2.getName());

}

});

System.out.println(l3);

}

}