In this article, we will understand how to find the duplicate characters in a string. String is a datatype that contains one or more characters and is enclosed in double quotes(“ ”).
Below is a demonstration of the same −
Suppose our input is −
Input string: Java Programming
The desired output would be −
The duplicate characters in the string are: a a r g m
Algorithm
Step 1 - START Step 2 - Declare a string namely input_string, a char array namely character_array. Step 3 - Define the values. Step 4 - Convert the string to character array. Step 5 – Iterate over the character_array twice with ‘i’ and ‘j’ values. Using an if-confition, check if ‘i’th value matches with the ‘j’th value. If yes, it’s a duplicate. Store the value. Step 5 - Display the result Step 6 - Stop
Example 1
Here, we bind all the operations together under the ‘main’ function.
public class Demo { public static void main(String argu[]) { String input_string = "Java Programming"; System.out.println("The string is defined as: " + input_string); char[] character_array = input_string.toCharArray(); System.out.print("\nThe duplicate characters in the string are: "); for (int i = 0; i < input_string.length(); i++) { for (int j = i + 1; j < input_string.length(); j++) { if (character_array[i] == character_array[j]) { System.out.print(character_array[j] + " "); break; } } } } }
Output
The string is defined as: Java Programming The duplicate characters in the string are: a a r g m
Example 2
Here, we encapsulate the operations into functions exhibiting object-oriented programming.
public class Demo { static void duplicate_characters(String input_string){ char[] character_array = input_string.toCharArray(); System.out.print("\nThe duplicate characters in the string are: "); for (int i = 0; i < input_string.length(); i++) { for (int j = i + 1; j < input_string.length(); j++) { if (character_array[i] == character_array[j]) { System.out.print(character_array[j] + " "); break; } } } } public static void main(String argu[]) { String input_string = "Java Programming"; System.out.println("The string is defined as: " + input_string); duplicate_characters(input_string); } }
Output
The string is defined as: Java Programming The duplicate characters in the string are: a a r g m