#95 Comparator vs Comparable in Java
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- Опубликовано: 17 янв 2023
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In this lecture we will learn:
- What is Comparator in Java?
- How to give your implementation for sorting?
- What is Comparable in Java?
- Difference between Comparable & Comparator
#1
- From the Java 1.7 version, it is not compulsory to mention the generic type on the right-hand side if you have already mentioned it on the left-hand side.
- A collection class has lots of methods. The collection class belongs to the util package.
- We can sort a list or an ArrayList by using the method sort of collection class
Collections.sort();
- If we want to apply our own logic in sorting, then we have to use a comparator with sorting in collections.
- Comparator is also an interface.
- We have a method called compare() in the comparator interface.
- We can use an interface by implementing a class or through an anonymous class.
- Compare method works on an algorithm where it compares two values and then swaps them.
Comparator Integer com= new Comparator Integer()
{
public int compare(Integer i, Integer j)
{
statements;
}
};
- So, a comparator is an interface through which you can specify your own concept of sorting.
#2
- Integer class implements a Comparable interface. So by default, sort works for Integer.
- If you want to do natural sorting on any other non-defined class, you can implement something called the Comparable.
- Comparable is present in the lang package.
- Comparable has a method known as compareTo().
- You have to define the method comapreTo() in a class, that is implementing Comparable.
class Student implements Comparable Student
{
public int compareTo( Student that){
statements;
}
}
Here, that is a variable.
- We can also override the logic by using Comparator even if we have implements the Comparable interface.
- Lambda expression can also be used with Comparator as it is a functional interface.
#3
Difference between Comparable & Comparator:
- Comparable provides a single sorting sequence while the Comparator provides multiple sorting sequences.
- In Comparable, actual gets modified while in Comparator, the original class does not get affected.
- Comparable gives the compareTo() method for sorting while Comparator gives the compare() method to sort elements.
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Наука
You literally teach and explain everything about sorting with object in 15 mins that my professor wasn't able to do in 2 hours. Good job and keep doing these things because it's really helpful and valuable to a fresher like me
So glad you're updating your older videos. Helpful as always! 😁
Hi Navin. as usual great video.. but most importantly comparator and comparable have always been things ive never understood.... until now.. the way you have explained is amazing and always wait for your amazing videos. and by the way the growth of your presentation and teaching skills have become better and better and we love it. Thanks a lot and will be waiting for lots more videos.
Good video. Thanks for leaving in the errors so we can learn.
Navin sir.... Really fond of u..... I sat for 5 hrs to understand it.... Now im crystal clear
Thank you Mr.
You made it very simple and easy!
wonderful video, it helps me to understand the concept very clear . Example you are providing is just awesome sir. keep doing these kind of videos sir. thanks a lot.
The last 2 mins are very insightful!! 😍😍
10/10 video and demonstration, absolutely love the dynamic, following along and coding beside you helps to learn efficiently
Love your videos, learn new thing every time.
Great explanation, thank you so much!
Thank you. very clear and helpful!
Heck of a video! I have been trying to understand the differences for a long time, finally you cleared all of my doubts.
Excellent ❤❤ , feeling enjoyed the functional usage at the end
Great, got my concepts cleared . Thank you , sir!!!👍👍👍👍👍👍👍👍👍👍👍👍👍👍
thanks for your explanation, sir. It helps me to understand comparable and comparator.
This is great explanation.
thats a great video
covered all that i needed thank you
best java instructor i’ve ever come across
Thank you for valuable video ❤️
Thanks for the awesome explanation sir🎉
Awesome Explanation!
Just discovered this video and the explanation is awesome, it almost blew my mind
Thank you so much for this.
i love you man. I finally got it!
I must say this was one of the best videos explaining comparator and comparable concept.
thank u sir very helpful . all clear now . Okay I have
This video is tooo goood. THANK you
amazing video, gave me the summary i needed!
Now, I understood those concepts. Thanks
Great Explanation. Thanks
Awesome guruji shukriya
Very good videoes!
Very helpful, thank you.
Great video, thanks !
How you intantiated the comparator because comparator is an interface and we cannot instantiate interface?
Understood today the real concept behind comparator and comparable
Hats off to you, sir! 🙌
Reddy ji! No words Thanks for your explanation
Nice explaination
Excellent video. Well explained. Can you add a comment here on how to sort based on more than one field? Say name and age assuming student names are duplicated. thanks
your videos are awesome man
great video sir
you know the person teaching you about java is legit when he is bald hehe. subscribed :)
My teacher in University who's teaching us java is also bald🤣 and he even looks so much like this youtuber!!
@telusko I loved your teaching style Naveen Reddy Sir,
It is not necessary for a Comparator to return -1 or 1 it can actually return any negative or positive integer only the sign matters. even 0 is allowed i guess.
this caused me confusion but you should have also mentioned it at the end for more nerdy people.
package java4AdvancedCollections;
import java.util.TreeSet;
public class TreeSetExample {
public static void main(String[] args) {
// Creating a TreeSet of integers (natural ordering)
TreeSet treeSet = new TreeSet();
// Adding elements to the TreeSet
treeSet.add(10);
treeSet.add(5);
treeSet.add(20);
treeSet.add(15);
// Printing the TreeSet (elements will be in ascending order)
System.out.println("TreeSet: " + treeSet);
// Creating a TreeSet with a custom comparator for descending order
TreeSet descendingTreeSet = new TreeSet((a, b) -> {
if (a > b) {
return -2;
} else {
return 2;
}
});
// Adding elements to the descending TreeSet
descendingTreeSet.add(10);
descendingTreeSet.add(5);
descendingTreeSet.add(20);
descendingTreeSet.add(15);
// Printing the descending TreeSet (elements will be in descending order)
System.out.println("Descending TreeSet: " + descendingTreeSet);
// Performing operations specific to NavigableSet interface
System.out.println("Ceiling of 12: " + treeSet.ceiling(12));
System.out.println("Floor of 12: " + treeSet.floor(12));
}
}
Nice explanation. which IDE is that ? - got it. Visual Studio
Great explanation
Sir what is meaning of 1 and -1 . I didn't understand that
Had to watch an entire tutorial just because I thought I don't undertand java. After this video. i'm like OH MY GOD !!!!!!!!!
Code for sorting string based on length of the string:
public static void main(String args[]) {
Comparator com = new Comparator() {
public int compare(String i, String j){
if(i.length() > j.length()){
return 1;
}
else{
return -1;
}
}
};
List strs = new ArrayList();
strs.add("Irene");
strs.add("Seulgi");
strs.add("Wendy");
strs.add("Joy");
strs.add("Yeri");
Collections.sort(strs, com);
System.out.println(strs);
}
// Output is [Joy, Yeri, Wendy, Irene, Seulgi]
Navin Reddy never disappoints
what if i try to implement Comparator on Student class, Navin reddy please explain this scenario
Thanx jhonny
Do we always need to use Array List for comparator or can it be used for array also??
I think no
We can use any collection
Correct me if I am wrong
Thanks
something meaningful to me
Cannot make a static reference to the non-static field compare
some times i am getting this error
in quick fix i got add static
static Comparator com = new Comparator() {
then it solved
I have a doubt .... how many times this swapping happens??
thanks
sir can u upload generics concept
you are the best
@telusko it is not necessary for a Comparator to return -1 or 1 it can actually return any negative or positive integer only the sign matters.
{even 0 is allowed i guess}
can any body tell me why return 1 and -1 is used .
Yes please..
How did you replace nums to studs?
its just find and replace
I have a quetion, why by returning 1 , the swapping is happenning?It doesn't make sense to me,plz explain
Hello! Returning 1 means that a is greater than b. Returning -1 means b is greater than a. Returning 0 means a equals b. I hope this helps!
Nuvu king mava🤗
Sir please try to make videos with white screen
Comparator is an interface so how object will created??
we are implementing the logic with lambda expression
Logic to sort elements based on the length of the string
import java.util.Comparator;
import java.util.*;
class Solution {
public static void main(String[] args) {
Comparator com = new Comparator(){
public int compare(String a , String b){
if(a.length() > b.length())
return 1;
else
return -1;
}
};
List nums = new ArrayList();
nums.add("Python");
nums.add("C++");
nums.add("Java");
nums.add("Django");
nums.add("SpringBoot");
nums.add("Spring");
Collections.sort(nums , com);
System.out.println(nums);
}
}
Sorting the String based on the length:
public class PractComparator {
public static void main(String[] arg) {
Comparator com = new Comparator() {
@Override
public int compare(String o1, String o2) {
return o1.length() - o2.length();
}
};
List fruit = new ArrayList();
fruit.add("Banana");
fruit.add("Mandarin");
fruit.add("PineApple");
fruit.add("Apple");
Collections.sort(fruit,com);
System.out.println(fruit);
}
}
1 for swap &
-1 for no swap
TASK :
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
class Hello {
public static void main(String a[]) {
Comparator com = new Comparator() {
public int compare(String i, String j)
{
if(i.length() < j.length())
return 1;
else
return -1;
}
};
List names = new ArrayList();
names.add("Navin");
names.add("Navin Reddy");
names.add("Telusko");
names.add("Navin Telusko");
Collections.sort(names, com);
System.out.println(names);
}
}
Correct 👍
You are awesome 👏👏👏
Sir the collection is not a class it's an Interface
Collections is a class but Collection is an interface 😊
what is the IDE he is using?
Vs code
but IntelliJ IDEA works better
When i was a student in 2015 then also i used to come and watch java videos here. I now have almost 5 years of experience and when some Java work comes I come here again to refresh my memory. Thank you Navin. It feels like nostalgia sometimes watching your videos
Synopsis:
If you want to give class the power to compare its object on its own then use Comparable otherwise use Comparator to define logic and pass its object in the Collections.sort() method....
14:03
opiest explaination
aaj mai alien banne vaala tha sir but aaj bhi merko aadhi cheeze samajh nahi aayi
Got lamda expression clear from u.
❤❤❤❤❤❤❤❤
What if two students have the same age?
Sorting string by length
package Collection;
import java.util.*;
public class SortStringByLen {
public static void main(String[] args) {
ArrayList ob = new ArrayList();
ArrayList ob1 = new ArrayList();
Comparator c1 = new Comparator() {
public int compare(String i ,String j){
if(i.length()>j.length()){
return 1;
}
else{
return -1;
}
}
};
Scanner sc = new Scanner(System.in);
System.out.println("Enter the names: ");
String str;
int len;
for(int i=0;i
You are explaining saying sort() works using bubblesort in the background, which need not be the case, don't give wrong info. In case of java it uses, duel pivot quick sort sort alogithm. Why you pass in comparator, you are only letting the sort know how to compare the values, not the whole sorting.
Ohh bhupendra jogi 😂😂😂
7:20
import java.util.List;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
public class compa {
public static void main(String[] args) {
Comparator y = new Comparator() {
public int compare(String i, String j) {
if (i.length() > j.length())
return 1;
else
return -1;
}
};
List names = new ArrayList();
names.add("Gnani");
names.add("Gnan");
names.add("Chapathi");
names.add("Gnanesh");
names.add("navin mava");
Collections.sort(names, y);
System.out.println(names);
}
}
Line no: 8 --> You have to specify Comparator on right side as well, its compulsory 3:03 . But I dono why it works without it.
@@codework2434 it's new update from official java it's unnecessary to mention on creating object of Comparator But in case of anonymous class we should!
do you understand?
@@sharabugnanesh3098 So, in your code above you left to mention the type, right ?
@@codework2434 yes I need to mention at left
@@sharabugnanesh3098 Thanks about the "official java update"
Thankyou Reddy Ji lots of love.
7:28
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
public class first {
public static void main(String[] args) throws IOException
{
Comparator comp = new Comparator() {
public int compare(String s, String t) {
if (s.length() < t.length())
return 1;
else
return -1;
// throw new UnsupportedOperationException("Unimplemented method 'compare'");
}
};
List col=new ArrayList();
col.add("aaaaa");
col.add("aa");
col.add("aaaa");
col.add("a");
Collections.sort(col, comp);
System.out.println(col);
}
}
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
public class ChallengLQREA {
public static void main(String[] args) {
Comparator cmp = new Comparator() {
public int compare(String o1, String o2) {
if(o1.length() < o2.length())
return -1;
else
return 1 ;
}
};
ArrayList SortStrings = new ArrayList();
SortStrings.add("Amine");
SortStrings.add("Saberrr");
SortStrings.add("Aichaa");
SortStrings.add("Bahtiiii");
Collections.sort(SortStrings,cmp );
System.out.println(SortStrings);
}
import java.util.List;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
public class Student {
public static void main(String[] args) {
Comparator com = ( i, j) -> s1.length()>s2.length()? 1 : -1;
List names = new ArrayList();
names.add("Nathan");
names.add("Dominic");
names.add("Nikita");
names.add("Sharon");
names.add("Jessica");
Collections.sort(names, com);
System.out.println(names);
}
}
Ternary Operator ❌ Tatari Operator ✔
Too greedy with the ads
package basics;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
public class demo {
public static void main(String[] args) {
Comparator com = new Comparator()
{
public int compare(String i, String j) {
if(i.length()
Fucking awesome❤
Homework:
import java.util.*;
class Solution {
public static void main(String[] args) {
// Write your code here
Comparator com=new Comparator(){
//jai mata di : Anonymous Inner class
public int compare(String s1, String s2){
if(s1.length()>s2.length()){
return 1;
}
else return -1;
}
};
List al=new ArrayList();
al.add("Rahul");
al.add("DK");
al.add("J");
Collections.sort(al,com);
System.out.println(al);
}
}
public class SortNamesByLength {
public static void main(String[] args) {
List names = new ArrayList();
names.add("Rashid Khan");
names.add("Rohit Sharma");
names.add("Babar Azam");
names.add("David Warner");
names.sort(Comparator.comparingInt(String::length));
for (String name : names) {
System.out.println(name);
}
}
}
package org.example.Strings;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
public class SortWithLength {
public static void main(String[] args) {
Comparator cp = new Comparator() {
public int compare(String i, String j) {
char[] ch = i.toCharArray();
char[] ch2 = j.toCharArray();
if(ch.length
w
// Sort the list of strings on the basis of length of string.
List list = new ArrayList();
list.add("Navin Reddy sir");
list.add("Harendra Pandey jee");
list.add("Gautam");
list.add("Nitesh");
Comparator com = new Comparator() {
@Override
public int compare(String o1, String o2) {
if(o1.length()>o2.length())return 1;
else return -1;
}
};
System.out.println("List before sorting");
System.out.println(list);
System.out.println("List after sorting");
Collections.sort(list,com);
System.out.println(list);