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Duplicate chars in a String
Print the duplicate characters in a given string.
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package com.bethecoder.tutorials.coding.examples;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
/**
* Print the duplicate characters in a given string.
*/
public class PrintDuplicateCharsTest {
/**
* @param args
*/
public static void main(String[] args) {
String str = "ABBACCCDEEEFKIKLKM";
System.out.println("Duplicates in '" + str + "' : " + getDuplicateChars(str));
str = "A";
System.out.println("Duplicates in '" + str + "' : " + getDuplicateChars(str));
str = "ACxxDDCA";
System.out.println("Duplicates in '" + str + "' : " + getDuplicateChars(str));
}
private static List<Character> getDuplicateChars(String str) {
Map<Character, Integer> map = new HashMap<Character, Integer>();
for (int i = 0 ; i < str.length() ; i ++) {
char c = str.charAt(i);
if (map.containsKey(c)) {
map.put(c, map.get(c) + 1); //duplicate found
} else {
map.put(c, 1); //first time found
}
}
Iterator<Character> it = map.keySet().iterator();
List<Character> duplicates = new ArrayList<Character>();
while (it.hasNext()) {
char c = it.next();
if (map.get(c) > 1) { //duplicate characters
duplicates.add(c);
}
}
return duplicates;
}
}
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It gives the following output,
Duplicates in 'ABBACCCDEEEFKIKLKM' : [E, A, B, C, K]
Duplicates in 'A' : []
Duplicates in 'ACxxDDCA' : [D, A, C, x]
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