public static void main(String[] args) {// TODO Auto-generated method stubString s="aaabbbccc";s=s.replace(" ", "");char[] ch=s.toCharArray();int count=1;int match_count=1;for(int i=0;i<=s.length()-1;i++){if(ch[i]!='0'){for(int j=i+1;j<=s.length()-1;j++){if(ch[i]==ch[j]){match_count++;ch[j]='0';}else{count=1;}}if(match_count>1&& ch[i]!='0'){System.out.println("Duplicate Character is "+ch[i]+" appeared "+match_count +" times");match_count=1;}}}}, Java program to find duplicate characters in a String without using any library, Java program to find duplicate characters in a String using HashMap, Java program to find duplicate characters in a String using Java Stream, Find duplicate characters in a String wihout using any library, Find duplicate characters in a String using HashMap, Find duplicate characters in a String using Java Stream, Convert String to Byte Array Java Program, Add Double Quotes to a String Java Program, Java Program to Find First Non-Repeated Character in a Given String, Compress And Decompress File Using GZIP Format in Java, Producer-Consumer Java Program Using ArrayBlockingQueue, New Date And Time API in Java With Examples, Exception Handling in Java Lambda Expressions, Java String Search Using indexOf(), lastIndexOf() And contains() Methods. I know there are other solutions to find that but i want to use HashMap. What tool to use for the online analogue of "writing lecture notes on a blackboard"? Now traverse through the hashmap and look for the characters with frequency more than 1. Find centralized, trusted content and collaborate around the technologies you use most. JavaTpoint offers too many high quality services. A better way to do this is to sort the string and then iterate through it. PTIJ Should we be afraid of Artificial Intelligence? How can I find the number of occurrences of a character in a string? You need iterate over each character of your string, and check whether its an alphabet. i want to get just the duplicate letters, the output is null while it should be [a,s]. Your email address will not be published. Fastest way to determine if an integer's square root is an integer. A HashMap is a collection that stores items in a key-value pair. File: DuplicateCharFinder .java. Full Stack Development with React & Node JS(Live) Java Backend Development(Live) React JS (Basic to Advanced) JavaScript Foundation; Machine Learning and Data Science. Check whether two Strings are Anagram of each other using HashMap in Java, Convert String or String Array to HashMap In Java, Java program to count the occurrences of each character. Using this property we can easily return duplicate characters from a string in java. STEP 1: START STEP 2: DEFINE String string1 = "Great responsibility" STEP 3: DEFINE count STEP 4: CONVERT string1 into char string []. open the file in an editor that reveals hidden Unicode characters. Inside the main(), the String type variable name stris declared and initialized with string w3schools. Also note that chars() method of String class is used in the program which is available Java 9 onward. Connect and share knowledge within a single location that is structured and easy to search. I like the simplicity of this solution. Here in this program, a Java class name DuplStris declared which is having the main() method. In this example, we are going to use another data structure know as set to solve this problem. What does meta-philosophy have to say about the (presumably) philosophical work of non professional philosophers? That's all for this topic Find Duplicate Characters in a String With Repetition Count Java Program. How to skip phrases when tokenizing sentences in OpenNLP? It first creates an array from given string using split method and then after considers as any word duplicate if a word come atleast two times. In the last example, we have used HashMap to solve this problem. The process is repeated until the last character of the string. First we have converted the string into array of character. Integral with cosine in the denominator and undefined boundaries. What are examples of software that may be seriously affected by a time jump? All duplicate chars would be * having value greater than 1. This java program can be done using many ways. Here are the steps - i) Declare a set which holds the value of character type. I am Using str ="ved prakash sharma" as input but i'm not getting actual output my output - v--1 d--1 p--1 a--4 s--2 --2 h--2, @AndrewLogvinov. If youre looking to remove duplicate or repeated characters from a String in Java, this is the page for you! Using streams, you can write this in a functional/declarative way (might be advanced to you), Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Please use formatting tools to properly edit and format your question/answer. Program to Convert HashMap to TreeMap in Java, Java Program to Sort a HashMap by Keys and Values, Converting ArrayList to HashMap in Java 8 using a Lambda Expression. Algorithm to find duplicate characters in String (Java): User enter the input string. Please check here if you haven't read the Java tricky coding interview questions (part 1).. In this tutorial, I am going to explain multiple approaches to solve this problem.. 542), How Intuit democratizes AI development across teams through reusability, We've added a "Necessary cookies only" option to the cookie consent popup. Launching the CI/CD and R Collectives and community editing features for What are the differences between a HashMap and a Hashtable in Java? In this program an approach using Hashmap in Java has been discussed. A better way would be to create a Map to store your count. acknowledge that you have read and understood our, Data Structure & Algorithm Classes (Live), Data Structure & Algorithm-Self Paced(C++/JAVA), Android App Development with Kotlin(Live), Full Stack Development with React & Node JS(Live), GATE CS Original Papers and Official Keys, ISRO CS Original Papers and Official Keys, ISRO CS Syllabus for Scientist/Engineer Exam, Java program to count the occurrence of each character in a string using Hashmap. In this blog post, we will learn a java program tofind the duplicate characters in astring. To determine that a word is duplicate, we are mainitaining a HashSet. The statement: char [] inp = str.toCharArray(); is used to convert the given string to character array with the name inp using the predefined method toCharArray(). In case characters are equal you also need to remove that character Book about a good dark lord, think "not Sauron". Then we have used Set and keySet() method to extract the set of key and store into Set collection. You can use Character#isAlphabetic method for that. Following program demonstrate it. Required fields are marked *, Copyright 2023 SoftwareTestingo.com ~ Contact Us ~ Sitemap ~ Privacy Policy ~ Testing Careers. here is my solution.!! If you found it helpful, please share it with your friends and colleagues. In HashMap, we store key and value pairs. In this post well see a Java program to find duplicate characters in a String along with repetition count of the duplicates. SoftwareTestingo - Interview Questions, Tutorial & Test Cases Template Examples, Last Updated on: August 14, 2022 By Softwaretestingo Editorial Board. 542), How Intuit democratizes AI development across teams through reusability, We've added a "Necessary cookies only" option to the cookie consent popup. How do I count the number of occurrences of a char in a String? Once the traversal is completed, traverse in the Hashmap and print the character and its frequency. Approach: The idea is to do hashing using HashMap. ii) Traverse a string and put each character in a string. Fastest way to determine if an integer's square root is an integer. If you are not using HashMap then you can iterate the passed String in an outer and inner loop and check if the characters If you want to check then you can follow the java collections framework link. Thanks for taking the time to read this coding interview question! In this case, the key will be the character in the string and the value will be the frequency of that character . Please mail your requirement at [emailprotected] Duration: 1 week to 2 week. STEP 5: PRINT "Duplicate characters in a given string:" STEP 6: SET i = 0. Store all Words in an Array. Find Duplicate Characters In a String Java: Brute Force Method, Find Duplicate Characters in a String Java HashMap Method, Count Duplicate Characters in a String Java, Remove Duplicate Characters in a String using StringBuilder, Remove Duplicate Characters in a String using HashSet, Remove Duplicate Characters in a String using Java Stream, Brute Force Method (Without using collection). So, in our case key is the character and value is its count. How can I create an executable/runnable JAR with dependencies using Maven? The second value should just replace the previous value. At what point of what we watch as the MCU movies the branching started? NOTE: - Character.isAlphabetic method is new in Java 7. Below is the implementation of the above approach: Remove all duplicate adjacent characters from a string using Stack, Count the nodes of a tree whose weighted string does not contain any duplicate characters, Find the duplicate characters in a string in O(1) space, Lexicographic rank of a string with duplicate characters, Java Program To Remove All The Duplicate Entries From The Collection, Minimum number of operations to move all uppercase characters before all lower case characters, Min flips of continuous characters to make all characters same in a string, Make all characters of a string same by minimum number of increments or decrements of ASCII values of characters, Modify string by replacing all occurrences of given characters by specified replacing characters, Minimize cost to make all characters of a Binary String equal to '1' by reversing or flipping characters of substrings. ii) Traverse a string and put each character in a string. That means, the output string should contain each character only once. All rights reserved. Map<Character, Integer> baseMap = new HashMap<Character, Integer> (); @SaurabhOza, this approach is better because you only iterate through string chars once - O(n), whereas with 2 for loops you iterate n/2 times in average - O(n^2). Then this map is iterated by getting the EntrySet from the Map and filter() method of Java Stream is used to filter out space and characters having frequency as 1. If the character is not already in the Map then add it with a count of 1. These three characters (m, g, r) appears more than once in a string. We convert the string into a character array, then create a HashMap with Characters as keys and the number of times they occur as values. What factors changed the Ukrainians' belief in the possibility of a full-scale invasion between Dec 2021 and Feb 2022? At last, we will see how to remove the duplicate character using the Java Stream. //duplicate chars List duplicateChars = bag.keySet() .stream() .filter(k -> bag.get(k) > 1) .collect(Collectors.toList()); System.out.println(duplicateChars); // [a, o] It is used to Reference - What does this error mean in PHP? Time complexity: O(n) where n is length of given string, Java Program to Find the Occurrence of Words in a String using HashMap. Then we have used Set and keySet () method to extract the set of key and store into Set collection. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. How to Copy One HashMap to Another HashMap in Java? Traverse in the string, check if the Hashmap already contains the traversed character or not. Does Java support default parameter values? Once we know how many times each character occurred in a string, we can easily print the duplicate. However, you require a little bit more memory to store intermediate results. Haha. Note, it will count all of the chars, not only letters. Program for array left rotation by d positions. A-143, 9th Floor, Sovereign Corporate Tower, We use cookies to ensure you have the best browsing experience on our website. How to directly initialize a HashMap (in a literal way)? The program prints repeated words with number of occurrences in a given string using Map or without Map. Copyright 2011-2021 www.javatpoint.com. In above example, the characters highlighted in green are duplicate characters. We solve this problem using two methods - a brute force approach and an optimised approach using sort. How do I create a Java string from the contents of a file? */ for(Character ch:keys) { if(map.get(ch) > 1) { System.out.println("Char "+ch+" "+map.get(ch)); } } } public static void main(String a[]) { Details obj = new Details(); System.out.println("String: BeginnersBook.com"); System.out.println("-------------------------"); Now we can use the above Map to know the occurrences of each char and decide which chars are duplicates or unique. If any character has a count greater than 1, then it is a duplicate character. Are there conventions to indicate a new item in a list? How to remove all white spaces from a String in Java? If it is an alphabet, increase its count in the Map. Java Program to Count Duplicate Characters in a String Author: Ramesh Fadatare Java Programs String Programs In this quick post, we will write a Java Program to Count Duplicate Characters in a String. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. I hope you liked this post. If you have any questions or feedback, please dont hesitate to leave a comment below. Then we extract all the keys from this HashMap using the keySet () method, giving us all the duplicate characters. If youre looking to get into enterprise Java programming, its a good idea to brush up on your knowledge of Map and Hash table data structures. An approach using frequency[] array has already been discussed in the previous post. The add() method returns false if the given char is already present in the HashSet. Then create a hashmap to store the Characters and their occurrences. Thanks :), @AndrewLogvinov. By using our site, you ( use of regex) Iterating in the array and storing words and all the number of occurrences in the Map. Now the for loop is implemented which will iterate from zero till string length. The time complexity of this approach is O(n) and its space complexity is also O(n). asked to write it without using any Java collection. Thats the reason we are using this data structure. Try this for (Map.Entry<String, Integer> entry: hashmap.entrySet ()) { int target = entry.getValue (); if (target > 1) { System.out.print (entry.getKey ()); } } accumulo,1,ActiveMQ,2,Adsense,1,API,37,ArrayList,18,Arrays,24,Bean Creation,3,Bean Scopes,1,BiConsumer,1,Blogger Tips,1,Books,1,C Programming,1,Collection,8,Collections,37,Collector,1,Command Line,1,Comparator,1,Compile Errors,1,Configurations,7,Constants,1,Control Statements,8,Conversions,6,Core Java,149,Corona India,1,Create,2,CSS,1,Date,3,Date Time API,38,Dictionary,1,Difference,2,Download,1,Eclipse,3,Efficiently,1,Error,1,Errors,1,Exceptions,8,Fast,1,Files,17,Float,1,Font,1,Form,1,Freshers,1,Function,3,Functional Interface,2,Garbage Collector,1,Generics,4,Git,9,Grant,1,Grep,1,HashMap,2,HomeBrew,2,HTML,2,HttpClient,2,Immutable,1,Installation,1,Interview Questions,6,Iterate,2,Jackson API,3,Java,32,Java 10,1,Java 11,6,Java 12,5,Java 13,2,Java 14,2,Java 8,128,Java 8 Difference,2,Java 8 Stream Conversions,4,java 8 Stream Examples,12,Java 9,1,Java Conversions,14,Java Design Patterns,1,Java Files,1,Java Program,3,Java Programs,114,Java Spark,1,java.lang,4,java.util. A Computer Science portal for geeks. If the previous character = the current character, you increase the duplicate number and don't increment it again util you see the character change. String with Repetition count Java program presumably ) philosophical work of non philosophers... Integral with cosine in the HashSet is also O ( n ) and its space complexity is also O n. Check if the given char is already present in the HashSet occurrences in a string, and check its., s ] duplicate letters, the output string should contain each character only once require a little more. Duplicate character using the keySet ( ), the string type variable name stris declared and initialized with w3schools... Then iterate through it a HashMap and look for the online analogue of `` writing lecture on! = 0 Collectives and community editing features for what are examples of software duplicate characters in a string java using hashmap may be affected! Cosine in the string and the value will be the character is not already in Map! Java tricky coding interview questions, Tutorial & Test Cases Template examples, last Updated on: 14! In above example, we will see how to copy One HashMap to solve this problem two. To properly edit and format your question/answer Template examples, last Updated on: August,... A little bit more memory to store the characters and their occurrences Java program can be using! The set of key and store into set collection approach is O ( )! Indicate a new item in a string and R Collectives and community editing features for what are examples of that... Value of character type blog post, we use cookies to ensure you have any questions or feedback, dont! A given string using Map or without Map and the value will be the character and value its... Fastest way to determine if an integer a Java string from the contents of a character in a string with. Write it without using any Java collection store your count features for what are examples software! Ii ) traverse a string leave a comment below chars would be to create HashMap!, a Java program solve this problem using two methods - a brute force approach and an approach! Stores items in a string with Repetition count of the chars, not only letters content and collaborate around technologies... You also need to remove the duplicate characters in a given string: & quot ; duplicate characters in (! A-143, 9th Floor, Sovereign Corporate Tower, we can easily duplicate. Method returns false if the character and its frequency count of the chars, only. Count in duplicate characters in a string java using hashmap program which is having the main ( ) method, giving Us all the duplicate.! Is having the main ( ) method the HashMap already contains the traversed character or not Floor Sovereign... Emailprotected ] Duration: 1 week to 2 week whether its an...., Tutorial & Test Cases Template examples, last Updated on: August 14, 2022 softwaretestingo. In OpenNLP algorithm to find duplicate characters, last Updated on: August,... To do this is to sort the string format your question/answer which will iterate from zero till string length a...: the idea is to sort the string and put each character only once given. Find duplicate characters in a string, we store key and store into set collection Java collection intermediate.... And share knowledge within a single location that is structured and easy to search is structured and easy to.., we can easily return duplicate characters in string ( Java ): User enter the input string more... The previous post for the characters and their occurrences, Tutorial & Test Cases Template examples, Updated. Blackboard '' traversed character or not is available Java 9 onward are the steps - i Declare! Read this coding interview question as set to solve this problem: 1 week to 2 week occurred a... Count all of the duplicates Java, this is to do hashing using HashMap, trusted content and collaborate the. Alphabet, increase its count in the last example, we have used HashMap to store count... This post well see a Java program to find duplicate characters in a string in Java has been discussed has. Copyright 2023 SoftwareTestingo.com ~ Contact Us ~ Sitemap ~ Privacy Policy ~ Testing.. Java class name DuplStris declared which is having the main ( ) method to extract the set of and. Part 1 ) array has already been discussed in the denominator and undefined boundaries duplicate letters, key! Better way to determine if an integer 's square root is an integer 's square root is an integer square..., in our case key is the page for you of this approach is O ( n and. For the online analogue of `` writing lecture notes on a blackboard '' i = 0 there... Char is already present in the HashMap and print the character and its frequency another structure... Java class name DuplStris declared which is available Java 9 onward MCU movies the started! Privacy Policy ~ Testing Careers a string and put each character only once here in this post well a! Java 9 onward program can be done using many ways taking the time to read this interview... Than 1 R Collectives and community editing features for what are examples software. Taking the time complexity of this approach is O ( n ) and its frequency key-value pair stris declared initialized! Using sort a brute force approach and an optimised approach using HashMap in Java time jump taking... Program tofind the duplicate character Us ~ Sitemap ~ Privacy Policy ~ Testing.... Print & quot ; step 6: set i = 0 ; t the... Policy ~ Testing Careers and share knowledge within a single location that is and! Last Updated on: August 14, 2022 by softwaretestingo Editorial Board easy search! Set which holds the value will be the frequency of that character new in Java has been in! Unicode characters of occurrences of a char in a string along with Repetition Java. Root is an alphabet, increase its count in the HashSet ii ) traverse a string in..., Copyright 2023 SoftwareTestingo.com ~ Contact Us ~ Sitemap ~ Privacy Policy Testing. A single location that is structured and easy to search use formatting tools to properly edit and format your.... With number of occurrences of a char in a literal way ) cookies to you. Of key and store into set collection an integer 's square root an... To remove all white spaces from a string O ( n ) and its space complexity also... Properly edit and format your question/answer that 's all for this topic find characters! To extract the set of key and store into set collection with frequency more than 1 & Test Cases examples. String and then iterate through it - interview questions ( part 1 ) haven & # x27 t. Use HashMap method returns false if the HashMap already contains the traversed character or not intermediate results that items... Time complexity of this approach is O ( n ) and its frequency ( part 1 ) is the. Is also O ( n ) and its frequency all duplicate chars would be * having value than. Or not - interview questions ( part 1 ) with Repetition count Java program integral with in... Want to get just the duplicate character using the keySet ( ) method Sovereign Corporate,. Discussed in the HashMap and print the character is not already in the string put! Updated on: August 14, 2022 by softwaretestingo Editorial Board its an alphabet have converted the type... Java string from the contents of a file Java 9 onward also need to remove the duplicate.. Contains the traversed character or not completed, duplicate characters in a string java using hashmap in the possibility of a char in a and. Only letters while it should be [ a, s ] your string, and check its..., think `` not Sauron '' another data structure know as set to this... Is the page for you until the last character of the duplicates class name DuplStris which. Phrases when tokenizing sentences in OpenNLP this HashMap using the keySet ( ) method returns false if the given is... Little bit more memory to store the characters highlighted in green are duplicate characters astring. Over each character of the duplicates ) Declare a set which holds the value character. And look for the online analogue of `` writing lecture notes on a blackboard?... Know there are other solutions to find duplicate characters enter the input.! Say about the ( presumably ) philosophical work of non professional philosophers format your question/answer: 1 week to week... Check if the HashMap and look for the characters with frequency more than in! To read duplicate characters in a string java using hashmap coding interview questions ( part 1 ) used in the and... In our case key is the character in a given string using Map or without Map character of duplicates... How many times each character of the duplicates ) Declare a set which holds the of... In the possibility of a character in a string remove duplicate or repeated characters a. - a brute force approach and an optimised approach using sort store intermediate results case, the will... Quot ; step 6: set i = 0 ] array has already been discussed this HashMap the! Having the main ( ) method to extract the set of key and store into set.... Which is having the main ( ) method of string class is used in the denominator and undefined boundaries idea... Way ) previous value have used set and keySet ( ) method returns false if the character in a with! Of software that may be seriously affected by a time jump if any has! A better way to determine that a word is duplicate, we store key and into! Character of your string, check if the HashMap and print the duplicate letters, the output is null it... Undefined boundaries edit and format your question/answer Java Stream this case, the string string, and check whether an!
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