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Java program to find all duplicate characters in a string
The duplicate characters in a string are those that occur more than once. These characters can be found using a nested for loop.
Problem Statement
Given a Java program to find the duplicate character in a given string.
Input
String = Tutorialspoint
Output
Duplicate Characters in above string are: t o i
In the above string, t o i are duplicate characters as it occurs more than once.
Approach to find all duplicate characters in a string
Below are the steps to find all duplicate characters in a string −
- Step 1: Convert the input string to a character array.
- Step 2: Use a nested loop to compare each character with the remaining characters in the array.
- Step 3: If a match is found, print the duplicate character.
- Step 4: Use a break statement to exit the inner loop once a duplicate is found to avoid printing duplicates multiple times.
- Step 5: Continue the process until all characters in the string have been checked.
Example
A program that demonstrates this is given as follows.
public class Example { public static void main(String argu[]) { String str = "beautiful beach"; char[] carray = str.toCharArray(); System.out.println("The string is:" + str); System.out.print("Duplicate Characters in above string are: "); for (int i = 0; i < str.length(); i++) { for (int j = i + 1; j < str.length(); j++) { if (carray[i] == carray[j]) { System.out.print(carray[j] + " "); break; } } } } }
Output
The string is:beautiful beach Duplicate Characters in above string are: b e a u
Code Explanation
Now let us understand the above program.
First, the string str is defined. Then, str.toCharArray() converts the string into a sequence of characters. The original string is displayed. The code snippet that demonstrates this is given as follows −
String str = "beautiful beach"; char[] carray = str.toCharArray(); System.out.println("The string is:" + str);
The duplicate characters are found in the string using a nested for loop. Then these characters are displayed. The code snippet that demonstrates this is given as follows.
System.out.print("Duplicate Characters in above string are: "); for (int i = 0; i < str.length(); i++) { for (int j = i + 1; j < str.length(); j++) { if (carray[i] == carray[j]) { System.out.print(carray[j] + " "); break; } } }