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Java String Exercises: Find first non repeating character in a string

Java String: Exercise-39 with Solution

Write a Java program to find first non repeating character in a string.

Pictorial Presentation:

Java String Exercises: Find first non repeating character in a string

Sample Solution:

Java Code:

import java.util.*;
public class Main {
 public static void main(String[] args) {
  String str1 = "gibblegabbler";
  System.out.println("The given string is: " + str1);
  for (int i = 0; i < str1.length(); i++) {
   boolean unique = true;
   for (int j = 0; j < str1.length(); j++) {
    if (i != j && str1.charAt(i) == str1.charAt(j)) {
     unique = false;
     break;
    }
   }
   if (unique) {
    System.out.println("The first non repeated character in String is: " + str1.charAt(i));
    break;
   }
  }
 }
}

Sample Output:

The given string is: gibblegabbler
The first non repeated character in String is: i

Flowchart:

Flowchart: Java String  Exercises - Find first non repeating character in a string

Visualize Java code execution (Python Tutor):


Java Code Editor:

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Previous: Write a Java program to print after removing duplicates from a given string.
Next: Write a Java program to divide a string in n equal parts.

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Java: Tips of the Day

Array vs ArrayLists:

The main difference between these two is that an Array is of fixed size so once you have created an Array you cannot change it but the ArrayList is not of fixed size. You can create instances of ArrayLists without specifying its size. So if you create such instances of an ArrayList without specifying its size Java will create an instance of an ArrayList of default size.

Once an ArrayList is full it re-sizes itself. In fact, an ArrayList is internally supported by an array. So when an ArrayList is resized it will slow down its performance a bit as the contents of the old Array must be copied to a new Array.

At the same time, it's compulsory to specify the size of an Array directly or indirectly while creating it. And also Arrays can store both primitives and objects while ArrayLists only can store objects.

Ref: https://bit.ly/3o8L2KH