To actually count the number of times that character would appear, you'll need to iterate over the string and count the number of times the selected character appears. 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Repeat char n times with Java repeated = new String (new char [n]).replace ("\0", c); Where n is the number of times you want to repeat the string and c is the character to repeat. Thank you for your valuable feedback! Learn to repeat a given string N times, to produce a new string which contains all the repetitions, though a simple Java program. How do I get the number of processors available to the JVM? Programming in Java, Spring, Hibernate / JPA. What are the differences between a HashMap and a Hashtable in Java? Java has a repeat function to build copies of a source string: String newString = "a" .repeat (N); assertEquals (EXPECTED_STRING, newString); This allows us to repeat single characters, or multi-character strings: String newString = "-->" .repeat ( 5 ); assertEquals ( "-->-->-->-->-->", newString); Recursive concatenation linear invocations (~30x). In this post, we are going to repeat a string N time using Java code. I know I could write this using a for loop, but I wish to avoid for loops whenever necessary and a simple direct method should exist somewhere. Java Stream reuse traverse stream multiple times? I don't think it's obfuscated at all. Using a pre-built function only tucks it under more covers. I'm looking for a simple commons method or operator that allows me to repeat some string n times. Learn Java Language - Repeat a String n times. How to Convert Comma Separated String to HashSet in Java? See. Printing a string N times We can do this in various ways. Using replace() method Use Strings replace() method to replace space with underscore in java. Find centralized, trusted content and collaborate around the technologies you use most. Your reasons for not using a for loop are not good ones. T is the generic type. Otherwise, we return the input string and concatenate it with the value returned by the recursive call. Given a char c and the desired number of repetitions count the following one-liner can do the same as above. Learn, how to repeat a string n times in Java. In this demo, i will show you how to create a snow fall animation using css and JavaScript. Find centralized, trusted content and collaborate around the technologies you use most. This creates n new string instances containing 1 to n repetitions of s resulting in a runtime of O(s.length() * n) = O(s.length() * (1+2++(n-1)+n)). Some of them are: Using for loop Taking input for N Using the repeat () method Print a string N number of times, once in each line in Java Here is an example, that repeats the string 'fox' 5 times. requires Java8. for the sake of readability and portability: If you are worried about performance, just use a StringBuilder inside the loop and do a .toString() on exit of the Loop. Indeed keep at least the entire code English (all identifiers; classnames, methodnames, variablenames). String.format() method to Repeat String N Times in Java. "I try to avoid for loops at all costs because" was added to the question as a clarification in response to Andrew Hare's answer after my reply - not that it matters because if the position you're taking is "answer is bad if loop is used. As the result you get the x character repeated 10 times. Thats the only way we can improve. Here is syntax of replace() method: [crayon-64c573bd68b3d408419238/] [crayon-64c573bd68b46456059485/] Output: 1 [], Table of ContentsJava StringsRemove Parentheses From a String Using the replaceAll() MethodRemove Parentheses From a String by TraversingConclusion Java uses the Strings data structure to store the text data. Or Apache commons has a utility class you can add. YT. Did active frontiersmen really eat 20,000 calories a day? Add a comment. return number > 0 ? Unless it's in some piece of code that will be executed thousands of times per second it won't make much difference. String.repeat () API [Since Java 11] How to create non-repeating Random String of size 5 using special characters (including space) only using java? This should really be marked as the answer. Are self-signed SSL certificates still allowed in 2023 for an intranet server running IIS? In this demo, we are going to learn about how to rotate an image continuously using the css animations. Sci fi story where a woman demonstrating a knife with a safety feature cuts herself when the safety is turned off. Practice SQL Query in browser with sample Dataset. This article is being improved by another user right now. String s = "qwe"; int n = 3; //this line print 'qweqweqwe'. Yes someone might add something clever, but by avoiding a for loop. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); document.getElementById( "ak_js_2" ).setAttribute( "value", ( new Date() ).getTime() ); HowToDoInJava provides tutorials and how-to guides on Java and related technologies. Please, never return null - in that case return an empty string, allowing you to always use the returned value unchecked. It is the simplest way to repeat the string. Thus it is required to work with arrays of chars. How do I avoid checking for nulls in Java? Thats all for the post, we took a deep dive into various methods that one can use to Repeat a String N Times in Java. Here is the shortest version (Java 1.5+ required): Where n is the number of times you want to repeat the string and s is the string to repeat. Do the 2.5th and 97.5th percentile of the theoretical sampling distribution of a statistic always contain the true population parameter? There are several ways to repeat to a string like using nCopies() method of Collections class or repeat() method or replace() method of string can also be used to get repeat string. For loops involving indexes tend to generate off by one bugs. 1. Join two objects with perfect edge-flow at any stage of modelling? It's in single quotes, not a variable. So, I decided to take two variants and see which one performed better. rev2023.7.27.43548. Save my name, email, and website in this browser for the next time I comment. If inserted in a method, arguments should be tested (times>=0), errors thrown etc.This adds robustness but also lines of code to read. How do I read / convert an InputStream into a String in Java? How to identify patterns of repeated characters within string? @TsuyoshiIto You use O() according to a unit operation you define. Connect and share knowledge within a single location that is structured and easy to search. This is perfectly clear in what it does and educational for those who may not see it right away. This method fills an array of char with a character. To avoid this StringBuilder should be used, which allows creating the String in O(s.length() * n) instead: Get monthly updates about new articles, cheatsheets, and tricks. String str = "abc"; String repeated = str.repeat (3); repeated.equals ("abcabcabc"); My girlfriend is planning to travel from Mexico City to Athens on Lufthansa connecting in Terminal 1 at Frankfurt Airport. String#repeat(int count), introduced as part of Java SE 11, makes it quite easy to do. Making statements based on opinion; back them up with references or personal experience. You could also repeatedly check that the character is in the string, get that index, then check the substring from after that index to the end of the string. Home > Core java > String > Repeat String N times in Java. Personal preference. Frankfurt, Germany. Has these Umbrian words been really found written in Umbrian epichoric alphabet? into a utility class in your project. While making each recursive call we decrease the counter N to reach the base condition. 1 year ago. java - What is the easiest way to generate a String of n repeated In Java, with the String replace()methodwe can define a Regular expression or a regex to modify any String. string - java repeat character - Stack Overflow Here is an O(logN) method, based on the standard binary powering algorithm: Negative values for reps return the empty string. Is it normal for relative humidity to increase when the attic fan turns on? Well, there are three ways to handle if s is null. Let's create an example to repeat a string. Webdriver simplest way to enter a longstring with sendKeys? How common is it for US universities to ask a postdoc to bring their own laptop computer etc.? So, you should write output = output.concat("!") @ChssPly76 my answers don't have any loops at all :-p. I don't think there is much else you can do excet maybe an AOT!! This explains the Immutability of String in Java. Now, without further ado let us outline different ways to solve this problem and explain each method in detail with examples. N Channel MOSFET reverse voltage protection proposal. So using '+=' as the 'unit' is really not such a good way of looking at it. Otherwise, what I would recommend the poster to use. Has these Umbrian words been really found written in Umbrian epichoric alphabet? Java Strings Java Strings is a class that stores the text data at contiguous [], Table of ContentsEscape Percent Sign in Strings Format Method in JavaEscape Percent Sign in printf() Method in Java In this post, we will see how to escape Percent sign in Strings format() method in java. and what hinders you to write a static method just like that? However, this will be very inefficient because building up a string of n exclamation marks will take O(n^2) time (look up "big oh notation" on google or wikipedia, see also Schlemiel the Painter's algorithm). There is a lot of knowledge and styles. I have to make a program that reads a number, and then displays that amount of exclamation mark "!". Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing. rev2023.7.27.43548. How does this compare to other highly-active people in recorded history? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing. Learn, how to repeat a string n times in Java. How do I efficiently iterate over each entry in a Java Map? This is a trick question common in JAVA interviews and the candidates evaluation is based on different approaches he/she provides for the problem. Not the answer you're looking for? We will use method Sting.repeat(N) (since Java 11) and using regular expression which can be used till Java 10. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Needless string reallocation, and recursion overhead bad, bad, not good. Let us look at the code implementation for this. Using String.repeat() method in Java 11 to Repeat String N Times, Regular Expression Regex to Repeat String N Times in Java, //creating char array of size n and then replace each value with str, Collections.nCopies() method to Repeat String N Times in Java. Using replace() method2. How to Set Direction to the Text in Cell using Java? Finding the farthest point on ellipse from origin? "Pure Copyleft" Software Licenses? Let us understand this with a code snippet. But since Java 11, you can use, Useful to know: commons-lang3 has a method taking a. How do I generate random integers within a specific range in Java? If regex is not what you are looking for then you can use StringUtils class and its method repeat(times). 594), Stack Overflow at WeAreDevelopers World Congress in Berlin, Temporary policy: Generative AI (e.g., ChatGPT) is banned, Preview of Search and Question-Asking Powered by GenAI. We pass the String to make copies of it. Recursive concatenation log2 invocations (~3x). The string can be repeated N number of times, and we can generate a new string that has repetitions. Repeat String N times in Java [8 ways] - Java2Blog rev2023.7.27.43548. Can you please add a description of why you believe this answers the question? The following Class can be used either with or without Separator-String/CharSequence and each call to "toString()" builds the final repeated String. What is Mathematica's equivalent to Maple's collect with distributed option? How do I show Spring transaction in log / console. Simple way to repeat a string (32 answers) Closed last year. Indeed this is not a perfect benchmark (a perfect benchmark simply doesn't exist) buy it clearly shows how slower the one method is compared with the other. If you are using Java <= 7, this is as "concise" as it gets: In Java 8 and above there is a more readable way: Finally, for Java 11 and above, there is a new repeat(int count) method specifically for this purpose(link). For loops increase the number of places a bug hunter has to look. When someone sees StringUtils.repeat, they know what I am doing. Making statements based on opinion; back them up with references or personal experience. Throw an NPE. Global control of locally approximating polynomial in Stone-Weierstrass? In Java 8, the introduction of theStream APIandLambda expressionshelped in minimizing the code and add more features of functional programming. What is telling us about Paul in Acts 9:1? Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing. Returns: String whose value is the concatenation of given String repeated count times. Despite your desire not to use loops, I think you should use a loop. It was designed for building up strings from parts. This is one of those cases. With the introduction of Java 11, a new utility method was added to the String class -> repeat() method. I am a java beginner, please keep that in mind. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Let us look at the syntax of declaring a String. replacing tt italic with tt slanted at LaTeX level? (note the loop in main function is to kick in JIT). Using replace() method2. (As in 1.5-2 hour wait for luggage) If you had travelled on that 3 hour connection to Venice last year and had to collect your luggage, you would likely have missed that flight. Use JMH for accurate results. Even if it is commented and has meaningful variables names, they still have to make sure it is not doing anything "clever". Data Structure & Algorithm Classes (Live), Data Structure & Algorithm-Self Paced(C++/JAVA), Full Stack Development with React & Node JS(Live), Top 100 DSA Interview Questions Topic-wise, Top 20 Interview Questions on Greedy Algorithms, Top 20 Interview Questions on Dynamic Programming, Top 50 Problems on Dynamic Programming (DP), Commonly Asked Data Structure Interview Questions, Top 20 Puzzles Commonly Asked During SDE Interviews, Top 10 System Design Interview Questions and Answers, Indian Economic Development Complete Guide, Business Studies - Paper 2019 Code (66-2-1), GATE CS Original Papers and Official Keys, ISRO CS Original Papers and Official Keys, ISRO CS Syllabus for Scientist/Engineer Exam. Pass the error (return null), 2. We can use the StringUtils class of the Apache Commons Library by importing with the following dependency. But we're looking at the difference between something that takes about 65 _micro_seconds and something that takes 305 _micro_seconds. To learn more, see our tips on writing great answers. In that case. By using InputStream#range () This method is added to the String class with the Java 11 version. Example. You can try these examples out at your local Java IDE. Required fields are marked *. How do I convert primitive data types into String? Big-O, not LoC. To test speed, a similar optimal method using StirngBuilder is like this: Note that the test for loop is to kick in JIT and have optimal results. Problem: Create a String containing n repetitions of a String s. The trivial approach would be repeatedly concatenating the String. This example show you how to create a repeated sequence of characters. very good!! First, the normal way to build up a String in Java is with the StringBuilder class, like this: Then, you need to declare a variable named output in the scope of the start() method, and assign the result of the printUitroeptekens() method to that variable, like this: There's nothing in the statement requiring you to actually build a string as far as I can tell. Connection times in Frankfurt Airport - Frankfurt Forum 4 reviews. It accepts two parameters: n -> the number of copies to make and the object to copy. The flights are: 1. How can i print a triangle with "*"s using for loop in java? Visibility (controlling access to members of a class). What is the use of explicitly specifying if a function is recursive or not? By clicking Post Your Answer, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Using Stream API to Repeat String N Times in Java, StringUtils Package Apache Commons Library to Repeat String N Times in Java. How do I convert a String to an int in Java? Look at the documentation to the StringBuilder class and use it. To learn more, see our tips on writing great answers. I'm a bit groggy today. 2. @e5;sorry for posting years later.I find this question so appropriate. Stay Up-to-Date with Our Weekly Updates. By using our site, you And that's for making a 100000 character String. 1 year ago. To learn more, see our tips on writing great answers. Using replace() method Use Strings replace() method to replace comma with space in java. 4 helpful votes. Again, so does whatever solution you use. If you can, use StringUtils from Apache Commons Lang: http://docs.guava-libraries.googlecode.com/git/javadoc/com/google/common/base/Strings.html. Would you publish a deeply personal essay about mental illness during PhD? If you do actually have the requirement to create a string which contains X number of exclamation marks, then here's a way to do it without repeated concatenation: Your program doesn't work because String.concat() does not change the string, but returns a new string. I am trying to make an hourglass in java as ASCII art who's height is controlled by a variable that I can change. This method will work: you can achieve your goal this way you're taking the integer s without any reason and what you're doing wrong is you are using .contains() method instead of that you should compare the given char with each char of the string and use a counter for maintaining number of times of the character or you can do it this way by converting the char into a string by concatenating it with an empty string("") and then use .equals method like i have used in my code. To do this we use the Arrays.fill () method. This modified text is an extract of the original, AppDynamics and TIBCO BusinessWorks Instrumentation for Easy Integration, Executor, ExecutorService and Thread pools, Java Editions, Versions, Releases and Distributions, Java Pitfalls - Nulls and NullPointerException, Parallel programming with Fork/Join framework, Splitting a string into fixed length parts, Comparing StringBuffer, StringBuilder, Formatter and StringJoiner. 5 Lines of code max. Sorry about downvoting. Drop me your questions related to how to repeat a string N times in Java. If the string is empty or the count is zero then the empty string is returned. Given a character c and a number n, how can I create a String that consists of n repetitions of c? Contribute to the GeeksforGeeks community and help create better learning resources for all. Using replaceAll() method Learn about how to replace comma with space in java. @Tedil: I don't want to reinvent the wheel. My edited answer is loop-free as requeted. 2. There is no way to do this in O(log N). Rather saying that by writing less code, and using library functions rather than reinventing the wheel I reduce the bug surface area(Lines of Code) while increasing readability. The problem states the following: given a string and a character by the user find the number of times the character (given by the user) repeats itself in the string (also given by the user). Using lastIndexOf() Method to Find Char in String in JavaFind Character at Index in String in Javahow Do I Find Word in String in Java? -1. Right into Your Inbox. returning a String with X repeated characters without a loop, Construct a string from a repeated character. Parameter: Accepts an integer count which is the number of times we want to repeat the string. This article discusses methods to remove parentheses from a String in Java. Report inappropriate content . Find Difference Between Two LocalDate in Java, Table of ContentsIntroductionUUID class in JavaConvert UUID to String in Java Introduction In this article, we will have a look on How to Convert UUID to String in Java. Let us look at the code for this as well. Note: We can also use the standard utility methods of the String Class with String literals, but the modifications will not reflect in the actual variable. How to handle repondents mistakes in skip questions? 555. Tagged java Leave a Reply Previous post Next post Follow for loop print - as many as the word length? Every iteration of that for loop will" call, New! If the string is empty or the count is zero then the empty string is returned. They are very often easy to get wrong. I'll remove the downvote as soon as I could (it's blocked until question is edited), @Nicolai source code for it, just in case someone cares. It's not even in the millisecond scale. I have to make a program that reads a number, and then displays that amount of exclamation mark "!". How do I use StringTokenizer to split a string? So here's the code if anybody wants to try it: It takes 2 arguments, the first is the number of iterations (each function run with repeat times arg from 1..n) and the second is the string to repeat. With java-8, you can also use Stream.generate. How do I create a repeated sequence of character? | Kode Java Given that we have to repeat a String that involves repeating a process over and over again, we can surmise that Recursion will be helpful to solve this problem. I don't think I've ever seen a project over 5000 LOCS that didn't have commons lang. We will also shed some light on the concept of UUID, its use, and its corresponding representation in Java class. replacing tt italic with tt slanted at LaTeX level? Using the String Object we can use the common utility methods provided by the String Class. Find centralized, trusted content and collaborate around the technologies you use most. You can use this recursive method for you desired goal. And it's worth noting: the code above does not contain an off-by-one error. New! Java - How to repeat a string n number of times? Previous owner used an Excessive number of wall anchors, Schopenhauer and the 'ability to make decisions' as a metric for free will. using only JRE classes (System.arraycopy) and trying to minimize the number of temp objects you can write something like: Not the shortest, but (i think) the fastest way is to use the StringBuilder: If speed is your concern, then you should use as less memory copying as possible. The British equivalent of "X objects in a trenchcoat". Subscribe now. I don't think this is so inefficient either, string concatenation isn't the warcrime it once was, because + really is just a stringBuilder UTH. 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