Java Program to find duplicate characters in a string

by Online Tutorials Library July 22, 2022

How do you find duplicate characters in a string?

Following program demonstrate it.

File: DuplicateCharFinder .java

  import java.util.HashMap;  import java.util.Map;  import java.util.Set;     public class DuplicateCharFinder {  public void findIt(String str) {  Map<Character, Integer> baseMap = new HashMap<Character, Integer>();  char[] charArray = str.toCharArray();  for (Character ch : charArray) {  if (baseMap.containsKey(ch)) {  baseMap.put(ch, baseMap.get(ch) + 1);  } else {  baseMap.put(ch, 1);  }  }  Set<Character> keys = baseMap.keySet();  for (Character ch : keys) {  if (baseMap.get(ch) > 1) {  System.out.println(ch + ”  is ” + baseMap.get(ch) + ” times”);  }  }  }     public static void main(String a[]) {  DuplicateCharFinder dcf = new DuplicateCharFinder();  dcf.findIt(“India is my country”);  }  }  

Output:

   is 3 times  i  is 2 times  n  is 2 times  y  is 2 times

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