In Java, here we are given a string, the task is to replace a character at a specific index in this string.
Examples:
Input: String = "Geeks Gor Geeks", index = 6, ch = 'F' Output: "Geeks For Geeks."
Input: String = "Geeks", index = 0, ch = 'g' Output: "geeks"
Method 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
public class GFG { 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
Method 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
public class GFG { 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
Method 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
public class GFG { 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
