Java Program to Replace a Character at a Specific Index

In this article, we will understand how to replace a character at a specific index. 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
Index: 6

The desired output would be −

Modified string: Java P%ogramming

Algorithm

Step 1 - START
Step 2 - Declare a string value namely input_string , an integer namely index, a char value namely character,
Step 3 - Define the values.
Step 4 - Fetch the substring from index 0 to index value using substring(), concatenate with character specified, concatenate this with the substring from ‘index + 1’. Store the result.
Step 5 - Display the result
Step 6 - Stop

Example 1

Here, we bind all the operations together under the ‘main’ function.

public class StringModify {
   public static void main(String args[]) {
      String input_string = "Java Programming";
      int index = 6;
      char character = '%';
      System.out.println("The string is defined as: " + input_string);
      input_string = input_string.substring(0, index) + character + input_string.substring(index + 1);
      System.out.println("\nThe modified string is: " + input_string);
   }
}

Output

The string is defined as: Java Programming

The modified string is: Java P%ogramming

Example 2

Here, we encapsulate the operations into functions exhibiting object-oriented programming.

public class StringModify {
   static void swap(String input_string, int index, char character){
      input_string = input_string.substring(0, index) + character + input_string.substring(index + 1);
      System.out.println("\nThe modified string is: " + input_string);
   }
   public static void main(String args[]) {
      String input_string = "Java Programming";
      int index = 6;
      char character = '%';
      System.out.println("The string is defined as: " + input_string);
      swap(input_string, index, character);
   }
}

Output

The string is defined as: Java Programming

The modified string is: Java P%ogramming