Reverse String in Java Practice Program #41

[@alexlorenlee]

If you’re new to programming but want a career in tech, I HIGHLY RECOMMEND applying to one of Springboard’s online coding bootcamps (use code ALEXLEE for $1,000 off): bit.ly/3HX970h

[@jorgerivera7008]

This channel is keeping me sane as I study for my Java Final next Monday!! Super underrated channel, cant wait for the blow-up!!

[@alexlorenlee]

Jorge Rivera thanks! Good luck!

[@remax110]

I agree, Alex does a very very good job with explaining especially for beginners like me. I'm glad to find this channel.

[@werren894]

if java can make dog to god, imagine what java could do to you

[@adarshmenon4356]

Lol

[@og_gaming2323]

lmao

[@zeeu]

Could also turn god into dog

[@ramosojustinken9894]

uoy

[@satyasrilekhagandreddy7766]

@@ramosojustinken9894 😂😂😂

[@vishy]

Really enjoyed working through this practice program ... will be working through the rest of your practice programs and tutorials! Please continue uploading programs and tutorials - they are invaluable. As always, thanks loads Alex!

[@qwerasdfhjkio]

I found an easier way! public String reverseString(String s) { String reversedString = ""; for (int i = s.length()-1; i >= 0; i--) reversedString += s.charAt(i); s = reversedString; return s; } Basically, you take a string as a parameter. Then you create an empty string. We'll need it later. Then, you start a loop which basically says to copy each character of "s" starting from the left to this empty string. then set "s" to the reversedString and return.

[@crazywarrior1232]

Hey Alex I have recently joined your discord server and wondered if u are available anytime as I have some questions as I have just started coding. Love your content by the way! Much easier to learn Java with you than any channel I have found before.

[@alexlorenlee]

Crazywarrior123 sure! I’ll hop over in the discord and I’ll see what I can help you with

[@marko8640]

Here's by far the simplest solution I've found so far (with user input): Scanner scan = new Scanner (System.in); System.out.println("Enter a String: "); String s = scan.nextLine(); System.out.println(new StringBuilder(s).reverse().toString());

[@subhakar9015]

new StringBuilder(s).reverse() is enough toString() no need

[@keithtammi2106]

Scanner scanner = new Scanner(System.in); System.out.print("Enter a Word: "); String r = reverse(scanner.nextLine()); System.out.println(r);

[@DriveandThrive]

@@keithtammi2106 you would still need to create a reverse method. private static String reverse(String nextLine) { StringBuilder stringBuilder = new StringBuilder(nextLine); return stringBuilder.reverse().toString(); } Then that would work.

[@dozui]

import java.util.Scanner; public class Main{ public static void main(String[] args){ Scanner s = new Scanner(System.in); System.out.print("Enter a String: "); String orig = s.nextLine(); s.close(); System.out.println("You entered : " + orig); System.out.println("Reversed to : " + reverseString(orig)); } static String reverseString(String input){ String result = ""; for(int i=input.length()-1; i>-1; i--) result = result + input.charAt(i); return result; } }

[@searemebrahtu8113]

public static void main(String[] arg){ String myStr = "hello"; String h =""; for(int i = myStr.length() - 1; i >= 0; i--){ h = h + myStr.charAt(i); } System.out.println(h); } Wouldnt this be easier?

[@sareer]

Exactly

[@kashivitagors7823]

public static void main(String[] args) { Scanner sc = new Scanner(System.in); String text; String tmp = ""; text = sc.nextLine(); for(int i=text.length()-1;i>=0;i--){ tmp+=text.charAt(i); } System.out.println("Result : "+tmp); }

[@reshmashaik3091]

You got a new subscriber from India

[@ItzKingzz]

I think this code is a lot easier, just so we don't have to use arrays: public class ReverseString { public static void main(String[] args) { String test = "dog"; // have the string "dog" reverse(test); // reverses and prints out dog } public static void reverse(String s){ StringBuilder result = new StringBuilder(); // creating a new string called result for (int h = s.length() - 1; h >= 0; h--) { // go through the s backwards result.append(s.charAt(h)); // appends or add the characters into our new string result } System.out.println(result); // print out the reverse version } }

[@ItzKingzz]

or you could simply have something like this: public class ReverseString { public static void main(String[] args) { String test = "dog"; // have the string "dog" reverse(test); // reverses and prints out dog } public static void reverse(String s){ for(int i = s.length() - 1 ; i >= 0 ; i--) { System.out.print(s.charAt(i)); } } }

[@hydrogennetwork]

that makes sense

[@linusziegler2413]

I gotta admit, learning with this channel is much more fun, keep it up :D

[@ClarkieReidri]

A more efficient way of coding this is to just make it one for loop to decrement through the initial String but making a int tempIndex starting at 0, counting through the decrements, to add each char to the array using the string constructor to pass the now reversed char array to a string.

[@morgvng8437]

simple, you chose god and dog because in italian its translated with "dio cane" a very common phrase here

[@thimiradk]

this method is very easy. look. public class ReverseString { public static void main(String[] args) { String str= "Hello World!"; String reverse= new StringBuilder(str).reverse().toString(); System.out.println(reverse); } }

[@latedeveloper7836]

This actually helped me more than the video - much more succinct and worked perfectly - thanks!

[@thimiradk]

@@latedeveloper7836 you welcome dr. 🙋

[@marko8640]

Wow. Both thumbs up!

[@zeeu]

public static String reverseStr(String str) { String finalStr = ""; for(int i=str.length()-1; i >= 0;i--) { finalStr += Character.toString(str.charAt(i)); } return finalStr; }

[@salaamdev]

public static void main(String[] args){ String rev = "hello"; for(int i = rev.length() -1; i >= 0; i--) System.out.println(rev.charAt(i)); }

[@randomguy3000]

public static void main(String [] args){ Scanner scan = new Scanner(System.in); String word = scan.nextLine(); String reverseWord=" "; for(int i=word.length()-1; i>=0; i--){ reverseWord+=word.charAt(i); } system.out.println(reverseWord); } this is another easier way to do it

[@marko8640]

Thank's for the code!

[@SS-ug1qy]

Why complicate when there is an easier way to reverse a string. String str = "Hello"; String reverse = ""; for(int i = str.length()-1; i>=0; i--) { reverse = reverse + str.charAt(i); } System.out.println(reverse); //if you want to check your string for palindrome you can add the bottom code. if(reverse.equalsIgnoreCase(str)) { System.out.println("word is a palindrome"); }else{ System.out.println("word is not a palindrome"); }

[@marko8640]

This is MASSIVELY helpful! Thank you!

[@mamtasingha6949]

You are great Alex, Really njoyed working with you... I can easily understand all your concepts ... It's supper fun Thank you ❤️

[@TomaAndreiMusic]

This code is cleaner and it does the same thing: class HelloWorld { public static void main(String[] args) { System.out.println(reverse("Alex")); } static String reversed = ""; public static String reverse(String s){ for(int i = s.length() - 1; i >= 0; i--){ reversed += s.charAt(i); } return reversed; } }

[@userx481]

Why not do this: String x = "Hare Krishna"; StringBuilder sb = new StringBuilder(); sb.append(x); System.out.println(sb.reverse()); Or this String input = "Gopinath"; char[] c = input.toCharArray(); for (int i = c.length-1; i>=0; i--) System.out.print(c[i]); And keep the brain fresh.

[@codegirl2069]

I've only thought of using a sb. Didn't know I could use .toCharArray Thanks :)

[@sotebis2608]

nice job!

[@petsgarden2945]

import java.util.*; public class Converter { public static void main(String[] args) { Scanner scan = new Scanner(System.in); scan.close(); String text = scan.nextLine(); StringBuffer buf = new StringBuffer(text); buf.reverse(); System.out.println(buf); } }

[@cjjsggsjsh8206]

you made that harder: package com.company; import java.util.Scanner; public class Game { public static void main(String[] args) { Scanner input = new Scanner(System.in); System.out.println("Enter The Word"); String word = input.next(); for (int i = (word.length()-1); i >=0; --i) System.out.print(word.charAt(i)); { } } }

[@marko8640]

Is there a way to reverse the whole sentence in that way? I'm new to Java, so everything I've tried so far failed miserably.

[@rittenbrake1613]

I think Alex can be patented as an cartoon character, super viewer friendly

[@estevanprado2005]

Could’ve just skipped the extra step of making a string and returned the array too right?

[@alexlorenlee]

Estevan Prado you could return the array but to print out an array you have to loop through it to get each element

[@estevanprado2005]

Alex Lee ohhhhh ok I see but you wouldn’t be able to read it using the ArraystoString method? Thanks for the feedback btw not hating or anything just want to see all the possible ways it could be done, I love coding too! 😊

[@alexlorenlee]

Estevan Prado haha I love coding too :) and yes you’re right, there are methods that’ll convert arrays to strings for ya that would do the same thing

[@irvingpurata2939]

Why do you need an other for loop if this one reverses the string? for(int i = str.length() -1 ; i > =0 ; i--) { System.out.print( str.charAt(i)); }

[@cartoons__for__kids_Hindi]

Yes but it stores it in a array of char, the other loop helps in putting that elements in a string.

[@kamalkaur1479]

Alex you know, I am beginner of java but after listen your video my enthusiasm is build up. I am really apricated by heart to see your amazing job

[@conanimation]

are u gonna do API like Lamda and Stremes ,btw grreat vids

[@marko8640]

Hey, there's another, much simpler way, by using String Buffer class. The beer's on you, guys. String One = "JavaTutorial"; StringBuffer sbuff = new StringBuffer(One); System.out.println(sbuff.reverse());

[@dafneylogan7433]

Awesome!!! It was so much simpler and it's easier to remember.

[@salaamdev]

i did this and worked, is it a must to do your way? public static void main(String[] args){ String rev = "hello"; for(int i = rev.length() -1; i >= 0; i--) System.out.println(rev.charAt(i)); }

[@ademgokce3136]

String myString = "AdemGokceKahramanmaras"; String myReverseString = new StringBuffer(myString).reverse().toString(); System.out.println("Here is myString: " + myString); System.out.println("Here is myReverseString: " + myReverseString);

[@user-sk4cw5lx4f]

Hello, I’m trying to reverse the order the lines from a text file. For example if the text file says “The cat in the hat Likes to eat Rats Because he’s so fat ” The output should be “Because he’s so fat Likes to eat Rats The cat in the hat “

[@mamaafrica2512]

public static String reverse(String s) { if(s.length() == 0) { return ""; } else { return s.charAt(s.length() - 1) + reverse(s.substring(0, s.length() - 1)); } } WITH RECURSION

[@vanamutt43]

Love your tutorials man. would this shorter bit of code be okay as well? achieves same result: String string = "Hello"; char buf; String reversed = ""; int i = string.length() - 1; while (i >= 0) { buf = string.charAt(i); reversed += String.valueOf(buf); i--; }

[@LizzieSpot]

Bro you made it a bit more hard because you can use print instead of println :- Code public class Main{ public static void main(String[] args){ String r = reverse("DOG"); } public static String reverse(String s){ char[] letters = new char[s.length()]; for(int i = s.length() - 1 ; i >= 0;i--){ System.out.print(s.charAt(i); // You should use print because it will print the whole // word in the single line/ } return s; } }

[@shirinelmanson7839]

Alex you are good teacher String name = "Shirin"; for (int i =name.length()-1;i>=0;i--) { System.out.print(name.charAt(i)); }

[@mohanrajpalanisamy2469]

{ String s="Dog",rev=""; Int l=s.length(); For(i=l-1;1>=0;1--) { rev=rev+s.charAt(i); } sysout(rev) }

[@MisterWealth]

Why is it s.length() - 1? What does the minis one do?

[@somkhit_phosavath]

Here's one of two ways I do reverse String: public static void reverseString() { String dog = "dog", dogs = ""; int reverse = dog.length(); for(int i = reverse - 1; i >= 0; i --) { dogs = dogs + dog.charAt(i); } System.out.println(dogs); }

[@pjguitar15]

String newStr = ""; for (int i = str.length() - 1; i >= 0; i--) { newStr += str.charAt(i); } return newStr; this solution is much easier in my opinion

[@AngieGiovanna]

omg i was finally able to run my first program after watching this video! this helped me so much!

[@dragomirpetrov5138]

Really sad that you decided to stop making Java tutorials. I believe you have a gift for teaching! Best wishes, man!

[@dimitarvelinov277]

@Dragomir Petrov, another Bulgarian here who agrees with you!

[@justmrfresh]

for(int i =str.length()-1;i>=0;i--)System.out.print(str.charAt(i));

[@techme1016]

Could you please solve this. Input : my name is arbaz Output: arbaz is name my

[@jenniferbijan1912]

thank the lord I found these videos. I'm currently taking a Data Structures and Algorithms course and I am L O S T.

[@anathadenver6027]

That was a great tutorial. I didn't expect that you'd explain how would the computer read the code. That made me easier to compose in my mind all the codes that you've written. Thank you so much.

[@Harshada1638]

Thank you so much

[@kvelez]

great program.

[@markk5495]

Great video. It really makes programming a lot more fun when doing programming exercises. Btw, what's wrong with the for (int i = s.length() - 1; i >= 0; i--){ System.out.println(s.charAt(i)); } ? I mean, the code worked fine and the result is good too. Why did you have to create another for-loop?

[@adenosinetp10]

just to show what else you can do

[@eien7228]

i still dont understand wht is the String reverse = ""; for

[@f3-faithfitnessfinance]

Initializing an empty string

[@f3-faithfitnessfinance]

@@ETSIRAVE in order to concatenate the characters of given string in reverse order..

[@AktherBrothersOfficial]

Which code is more efficient, the one in video or the one below? String text = sc.nextLine(); int[] chars = text.chars().toArray().clone(); for(int i=chars.length-1; i>=0; i--) { char c = (char)chars[i]; result += c; }

[@CorporateGamer]

I ended up walking away as a better person. Thanks

[@indranildutta4252]

made this code to have ask for input --- works charm

[@shaccc3728]

This is briefly how I did it: for (int i = len -1; i > 0; i--) { rev += norm.charAt(i); }

[@shykhsaif8781]

You are a good programmer but not a good teacher Don't jump through the video but try to explain it .

[@samarthvs3338]

A less complex method- public class Main { static String reverse(String s) { String reversed = ""; for(int i = s.length()-1; i >= 0; i--){ reversed = reversed + s.charAt(i); } return reversed; } public static void main(String[] args) { System.out.println(reverse("0123456")); } }

[@kakashi99908]

yeah the char array was totally unnecessary and added more complexity.

[@veervikramsingh8911]

sir How have you written String r = reverse("dog");

[@keanaleong7745]

Hello Alex. Line 15 at 9:26 would it be correct to have something like letters[0] instead of creating the letterIndex variable in line 13?

[@krm.073]

with the variable letterIndex you have some sort of counter for the reversed string/the char array. you start at index 0 and go up thus filling the array slots bit by bit with the characters of the string you want to reverse. if you used 0 or any constant number instead, you would redifine the character at the same slot with each itteration instead of moving to the next slot. (it's been 1 year but i still hope this was helpfull haha)

[@MrEvol94]

"Return" doesn't seem to exist in my java program 😅

[@sheenvelayudhanrajeswari579]

Just a modified way: public static String reverseString(String inpStr) { char[] reverChar = new char[inpStr.length()]; for(int chrIndx=0, i = inpStr.length()-1; i>=0; i--, chrIndx++) { reverChar[chrIndx] = inpStr.charAt(i); } return String.valueOf(reverChar); }

[@bennevisson7787]

can u please make a video on the USSDMenu program

[@georgietrottier9312]

I found a short and simple way Scanner n= new Scanner(System.in); System.out.print(“Enter Something: “); String name= n.nextLine(); char[] arr = new char[name.length()]; int k=0; for(int i=name.length() -1; i>=0; i-){ char last= name.charAt(i); arr (k)= last; k++; } System.out.print(arr);

[@gnanechaithu9738]

I think I am very late to discover this channel. Please cover dsa also.

[@sheetalpatil8591]

Why there is a second for each loop can u tell in first only we are taking the character in reverse order can not we directly print?

[@imtiazbasha3324]

Amazing and crystal clear explanation. Really enjoyed this practice program. Thank you Alex

[@hammershigh]

A few questions: 1. line 11 - Is char array an object, since you use "New"? 2. line 21 - Does the + operator add ANY datatype to a string, since letters[i] is a char? Great videos, btw :)

[@sahilparmar8382]

+ is used to concate string here letters

[@CrazyChaosClara]

Might be a stupid question... but why can't I create another string and call the method by writing s.reverse?

[@marko8640]

It's a totally valid question because I tried to do something similar in my code. It didn't work, so here I am, looking here for help. It bothers me, why it can't be simpler, like writing just a line or two of code. It's just writing a sentence backward.

[@kamalkaur1479]

can you please also help me Convert roman number to integer number?

[@richardsonmoraes2893]

the best java channel of all youtube.

[@rafaelnistor1652]

StringBuffer sb = new StringBuffer("My String"); System.out.println(sb.reverse());

[@marinastr3429]

Thank you very much for this video! I am studying applied informatics and I’m in the first semester. During corona everything‘s a little complicated, so I’m even more glad that you uploaded this tutorial. Have a good one! ☺️

[@emrekorkmaz5469]

you can basiclly write print instead of println?

[@sajedamirza6252]

Hi, is it possible for you to organize java tutorials and java OOP tutorials separately. So that , it would be easier to find. Thanks. You are doing great!

[@mjbuenaventura8169]

1. Create a program that will let the user to enter decimal numbers and will sort the inputted values into descending order. Make sure that the user will be able to decide how many numbers he or she wanted to enter. Use one dimensional array. 2. Create a program that will let the user to enter decimal numbers and will sort the inputted values into ascending order. Make sure that the user will be able to decide how many numbers he or she wanted to enter. Use one dimensional array. 3. Using the following initial values, 90,87,1,99,34,23,1000 and 78, create a program that will search where an element is located on an index of the array. 4. Create a program that will let the user to enter decimal numbers and will search and display the location of an element. hello I'm a student also a beginner and I don't know how to solve this problems. thank you😇

[@shives179]

how to use input hello world and output world hello in java

[@DMPDEV]

hey @Alex Lee, thanks for the help, I`ve been looking all around, and you are the best at it. Short and to the point. Anyway, I´m using Netbeans, not Eclipse. cause of school. so for some reason, its not working. It aint broken, it´s just not printing what it is supposed to. public static void main(String[] args) { String r = reverse("dog"); System.out.println(r); } public static String reverse(String s) { int i; = 0 ; i--){ letterIndex = s.charAt(i); letterIndex++; } String reverse = ""; return reverse; } so if you , or anyone in the comments could help out I would really appreciate it. Thanks, *firm handshake from Argentina

[@TheBoDuddly]

Great tuts as always....you could simplify this one though and not even use a char array. Just concatenate the charAt(i) straight into your empty string and return the result. :) public static String reverse(String s){ String result = ""; for (int i = s.length() -1; i>=0; i--){ result += s.charAt(i); } return result; }

[@sesebere]

Is believe he's aware this but doesn't want to do anything advanced for this tutorial, for the sake of beginners

[@eduartzina]

hello, i may need some help here with a code i got. I have 2 string arrays with names. from a method, I feed with 2 string Arrays and return strings with names, and by using "string.join" I have to print all names present in arrays . any idea how to solve this?

[@udayendubose1166]

This guy got my intrest in computer science

[@flashinstincts5032]

i think u are an angel. u are amazing. i learn how helpful humans are from ur kind work.

[@grenouilleflamboyante978]

great video. I tried to do it with Stack: public static String ReverseWithStack( String s) { LinkedList letter = new LinkedList(); String reverse = ""; for (int i = 0 ; i < s.length() ; i++) { letter.addFirst(s.charAt(i)); } for (int i = 0 ; i < letter.size(); i++) { reverse = reverse + letter.get(i); } return reverse; } It works but having 2 for loops that look similar bothers me

[@himusardar8329]

I didn't like the dog & god example. But I understood the method. Thanks for that ❤️.

[@DC-xj2fe]

Used this week 2 day 2 of Revature Java training. Very helpful. Thanks!

[@fizzics5588]

where is that keyboard from??

[@monicapacheco933]

Love your video, Thanks

[@MOLOTONO]

Good for interviews!!!

[@parvezquazi6424]

best explanation on whole youtube

[@cabreraaubrey4569]

is it with return and with parameter method?

[@yashwanthpraveen6798]

This is like the most complicated version of explanation for an easy problem.

[@rohatergun]

Nice code but overcomplicated

[@trazzysingh]

Hey i run like this public static String reverse(String str){ String return_revers= ""; if (str.isEmpty()) { str = return_revers; } char[] revers = new char[str.length()]; for (int i = revers.length - 1; i >= 0; i--) { return_revers +=str.charAt(i); } return return_revers; }

[@oliverdivine5246]

your peripherals sound horrible

[@highwired7781]

I've fallen in love with you

[@GenjaOrigins]

Very Good i had some problems on learning how to use Eclipse but very good video. I need examples.

[@GenjaOrigins]

But why you just dont return letters?

[@pokemonbakogan7442]

hi , thank you for the explaing , but can you plz explain how to create A program in which all arguments passed to the input string are displayed in reverse order. For example, if 2 arguments were passed - make install, then llatsni ekam should be displayed. Note *: to parse a word by letter, you must use the charAt () function. For example, str.charAt (i) will return the character at position i in the word written to the string variable str. Str command

[@blairgroove1302]

I wish I was as skillful as you are

[@swedishguyonyoutube4684]

Much appreciated! /First year CS student!

[@volkancamas986]

Hi Alex , Instead of the for loop you wrote at 6:42, we can reach the result by creating a string as follows. I wanted to write to support. Which one is better for performance, I don't know :) String reversedString = new String(letters); return reversedString;

[@rikkoo]

he couldve used reversedString += charAt(i) while decrementing the i or even used a StringBuilder, thats beyond the point, its only to teach you the logic, did i mention its free?