Write a Java Program to replace First Character Occurrence in a String with an example. In this Java replace first Occurrence of a Character example, we compare each character in repstCharStr string with the replace_ch. If they are equal, we assigned new_ch in that index position followed by break statement to exit from the While loop.
import java.util.Scanner; public class ReplaceFirstCharOccur1 { private static Scanner sc; public static void main(String[] args) { String repstCharStr; char replace_ch, new_ch; int i = 0; sc= new Scanner(System.in); System.out.print("\nPlease Enter any String = "); repstCharStr = sc.nextLine(); System.out.print("\nEnter the Character to Replace = "); replace_ch = sc.next().charAt(0); System.out.print("\nEnter the New Character = "); new_ch = sc.next().charAt(0); char[] repstCharArr = repstCharStr.toCharArray(); while(i < repstCharArr.length) { if(repstCharArr[i] == replace_ch) { repstCharArr[i] = new_ch; break; } i++; } System.out.format("\nThe Final String after replacing %c with %c = ", replace_ch, new_ch); System.out.print(repstCharArr); } }
Java replace first character occurrence in a String output
Please Enter any String = Java
Enter the Character to Replace = a
Enter the New Character = M
The Final String after replacing a with M = JMva
Java Program to Replace First Character Occurrence in a String Example 2
This Java replace the first occurrence of a character example is the same as the above, and we replaced the While loop with For Loop.
import java.util.Scanner; public class ReplaceFirstCharOccur2 { private static Scanner sc; public static void main(String[] args) { String repstCharStr; char replace_ch, new_ch; sc= new Scanner(System.in); System.out.print("\nPlease Enter any String = "); repstCharStr = sc.nextLine(); System.out.print("\nEnter the Character to Replace = "); replace_ch = sc.next().charAt(0); System.out.print("\nEnter the New Character = "); new_ch = sc.next().charAt(0); char[] repstCharArr = repstCharStr.toCharArray(); for(int i = 0; i < repstCharArr.length; i++) { if(repstCharArr[i] == replace_ch) { repstCharArr[i] = new_ch; break; } } System.out.format("\nThe Final String after replacing %c with %c = ", replace_ch, new_ch); System.out.print(repstCharArr); } }
Please Enter any String = Programming
Enter the Character to Replace = r
Enter the New Character = K
The Final String after replacing r with K = PKogramming
The replaceFirst is a string function that replaces the first occurrence of a charter with the new character.
import java.util.Scanner; public class ReplaceFirstCharOccur3 { private static Scanner sc; public static void main(String[] args) { String repstCharStr; String replace_ch, new_ch; sc= new Scanner(System.in); System.out.print("\nPlease Enter any String = "); repstCharStr = sc.nextLine(); System.out.print("\nEnter the Character to Replace = "); replace_ch = sc.nextLine(); System.out.print("\nEnter the New Character = "); new_ch = sc.nextLine(); String x = repstCharStr.replaceFirst(replace_ch, new_ch); System.out.format("\nThe Final String after replacing %s with %s = %s", replace_ch, new_ch, x); } }

We can use the Java String substring function to replace the first character occurrence. In this Java program, repstCharStr.substring(0, i) returns substring up to the index position of the replace_ch character. Next, we added the new_ch to it. Then, we used another substring repstCharStr.substring(i + 1, repstCharStr.length() to concat string from i to the end of that string.
import java.util.Scanner; public class ReplaceFirstCharOccur4 { private static Scanner sc; public static void main(String[] args) { String repstCharStr; String replace_ch, new_ch; sc= new Scanner(System.in); System.out.print("\nPlease Enter any String = "); repstCharStr = sc.nextLine(); System.out.print("\nEnter the Character to Replace = "); replace_ch = sc.nextLine(); System.out.print("\nEnter the New Character = "); new_ch = sc.nextLine(); int i = repstCharStr.indexOf(replace_ch); String x = repstCharStr.substring(0, i) + new_ch + repstCharStr.substring(i + 1, repstCharStr.length() ); System.out.format("\nThe Final String after replacing %s with %s = %s", replace_ch, new_ch, x); } }
Please Enter any String = Learn Java
Enter the Character to Replace = a
Enter the New Character = Q
The Final String after replacing a with Q = LeQrn Java
Please refer to the following string programs.
- Count the Total Occurrence of a Character in a String
- Find All Occurrences of a Character in a String
- First Character Occurrence in a String
- Remove First Character Occurrence in a String
- Last Character Occurrence in a String
- Replace Last Character Occurrence in a String
- Remove the Last Character Occurrence in a String
- First and Last Character in a String
- Remove The First and Last Character in a String
- Maximum Occurring Character in a String
- Minimum Occurring Character in a String
- Frequency of each Character in a String
- Remove All Occurrences of a Character in a String