How do you find duplicate characters in a string in Java without using collections?

How do you find duplicate characters in a string in Java without collection?


  1. Create a HashMap and character of String will be inserted as key and its count as value.
  2. If Hashamap already contains char,increase its count by 1, else put char in HashMap.
  3. If value of Char is more than 1, that means it is duplicate character in that String.

How do I find a repeated character in a string?

An efficient solution is to use Hashing to solve this in O(N) time on average.

  1. Create an empty hash.
  2. Scan each character of input string and insert values to each keys in the hash.
  3. When any character appears more than once, hash key value is increment by 1, and return the character.

How are duplicate characters found in a string in Java?

The duplicate characters are found in the string using a nested for loop. Then these characters are displayed.

How do I find duplicates in a string in Java 8?

In Java 8 Stream, filter with Set. Add() is the fastest algorithm to find duplicate elements, because it loops only one time. Set<T> items = new HashSet<>(); return list.


How do you remove duplicate characters in a string in Java?

1) By using for loop

  1. In the first step, we have to convert the string into a character array.
  2. Calculate the size of the array.
  3. Call removeDuplicates() method by passing the character array and the length.
  4. Traverse all the characters present in the character array.
  5. Check whether the str[i] is present before or not.

How do I reverse a string?

Different ways to find the reverse of a string in the C

  1. Reverse a string using the strrev() function.
  2. Reverse a string without using the library function.
  3. Reverse a string using the recursion function.
  4. Reverse a string using for loop.
  5. Reverse a string using while loop.
  6. Reverse a string using pointers.

How do I find duplicate characters in a string in SQL Server?

SQL Server: Count Number of Occurrences of a Character or Word in a String

  1. DECLARE @tosearch VARCHAR(MAX)=’In’
  2. SELECT (DATALENGTH(@string)-DATALENGTH(REPLACE(@string,@tosearch,”)))/DATALENGTH(@tosearch)
  3. AS OccurrenceCount.

How do you find the most repeated word in a string?


  1. STEP 1: START.
  2. STEP 2: DEFINE String line, word = “”
  3. STEP 3: SET count =0, maxCount =0.
  4. STEP 4: DEFINE ArrayList<String> words.
  5. STEP 5: USE File Reader to open file in read mode.
  6. STEP 6: READ line from file.
  7. STEP 7: By looping, CONVERT each line into lower case.
  8. STEP 8: REMOVE the punctuation marks.

How do you duplicate a string in Java?

repeated = new String(new char[n]). replace(“

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