Replace a character at a specific index in a String in Java
In Java, here we are given a string, the task is to replace a character at a specific index in this string.
Examples of Replacing Characters in a String
Input: String = "Geeks Gor Geeks", index = 6, ch = 'F'
Output: "Geeks For Geeks."
Input: String = "Geeks", index = 0, ch = 'g'
Output: "geeks"
Methods to Replace Character in a String at Specific Index
There are certain methods to replace characters in String are mentioned below:
- Using String Class
- Using StringBuilder
- Using StringBuffer
1. Using String Class
There is no predefined method in String Class to replace a specific character in a String, as of now. However, this can be achieved indirectly by constructing a new String with 2 different substrings, one from the beginning till the specific index – 1, the new character at the specific index, and the other from the index + 1 till the end.
Below is the implementation of the above approach:
Java
// Driver Classpublic class GFG { // main function public static void main(String args[]) { // Get the String String str = "Geeks Gor Geeks"; // Get the index int index = 6; // Get the character char ch = 'F'; // Print the original string System.out.println("Original String = " + str); str = str.substring(0, index) + ch + str.substring(index + 1); // Print the modified string System.out.println("Modified String = " + str); }} |
Original String = Geeks Gor Geeks Modified String = Geeks For Geeks
2. Using StringBuilder
Unlike String Class, the StringBuilder class is used to represent a mutable string of characters and has a predefined method for change a character at a specific index – setCharAt(). Replace the character at the specific index by calling this method and passing the character and the index as the parameter.
Below is the implementation of the above approach:
Java
// Java Program to replace character in// a String using StringBuffer// Driver Classpublic class GFG { // main function public static void main(String args[]) { // Get the String String str = "Geeks Gor Geeks"; // Get the index int index = 6; // Get the character char ch = 'F'; // Print the original string System.out.println("Original String = " + str); StringBuilder string = new StringBuilder(str); string.setCharAt(index, ch); // Print the modified string System.out.println("Modified String = " + string); }} |
Original String = Geeks Gor Geeks Modified String = Geeks For Geeks
3. Using StringBuffer
Like StringBuilder, the StringBuffer class has a predefined method for this purpose – setCharAt(). Replace the character at the specific index by calling this method and passing the character and the index as the parameter. StringBuffer is thread-safe and can be used in a multi-threaded environment. StringBuilder is faster when compared to StringBuffer, but is not thread-safe.
Below is the implementation of the above approach:
Java
// Java Program to replace character in// a String using StringBuffer// Driver Classpublic class GFG { // main function public static void main(String args[]) { // Get the String String str = "Geeks Gor Geeks"; // Get the index int index = 6; // Get the character char ch = 'F'; // Print the original string System.out.println("Original String = " + str); StringBuffer string = new StringBuffer(str); string.setCharAt(index, ch); // Print the modified string System.out.println("Modified String = " + string); }} |
Original String = Geeks Gor Geeks Modified String = Geeks For Geeks
