Java Program to Replace Multiple Characters in a String
In this program, we will be discussing various methods for replacing multiple characters in String. This can be done using the methods listed below:
- Using String.replace() method
- Using replaceAll() method
- Using replaceFirst() method
Method 1: Using String.replace() method
This method returns a new string resulting from replacing all occurrences of old characters in the string with new characters.
Syntax:
public String replace(char oldch, char newch)
Parameters:
- The old character.
- The new character.
Return Value: It returns a string derived from this string by replacing every occurrence of old character with a new character.
Example
// Java code to demonstrate the
// working of replace()
public class rep1 {
public static void main(String args[]) {
// Initialising String
String Str = new String("Welcome to geeksforgeeks");
// Using replace to replace characters
System.out.print("After replacing all o with T : " );
System.out.println(Str.replace('o', 'T'));
// Using replace to replace characters
System.out.print("After replacing all e with D : " );
System.out.println(Str.replace('e', 'D'));
}
}
Output
After replacing all o with T : WelcTme tT geeksfTrgeeks After replacing all e with D : WDlcomD to gDDksforgDDks
Method 2: Using replaceAll() method
This method replaces each substring of the string that matches the given regular expression with the given replace_str.
Syntax:
public String replaceAll(String regex, String replace_str)
Parameters:
- regex: the regular expression to which this string is to be matched.
- replace_str: the string which would replace found expression.
Return Value: This method returns the resulting String.
Example
// Java code to demonstrate the
// working of replaceAll()
public class rep2 {
public static void main(String args[]) {
// Initialising String
String Str = new String("Welcome to geeksforgeeks");
// original string
System.out.print("Original String : " );
System.out.println(Str);
// Using replaceAll to replace regex with replace_str
System.out.print("After replacing regex with replace_str : " );
System.out.println(Str.replaceAll("(.*)geeks(.*)", "AKSHIT SAXENA"));
}
}
Output
Original String : Welcome to geeksforgeeks After replacing regex with replace_str : AKSHIT SAXENA
Method 3: Using replaceFirst() method
This method replaces the first substring of this string that matches the given regular expression with the given replace_str.
Syntax:
public String replaceFirst(String regex, String replace_str)
Parameters
- regex: The regular expression to which this string is to be matched.
- replace_str: The string which would replace found expression.
Return value: This method returns a resulting string.
Example
// Java code to demonstrate the
// working of replaceFirst()
public class rep3 {
public static void main(String args[]) {
// Initialising String
String Str = new String("Welcome to geeksforgeeks");
// original string
System.out.print("Original String : " );
System.out.println(Str);
// Using replaceFirst to replace regex with replace_str
// Replaces 1st occurrence of geeks with ASTHA
System.out.print("After replacing 1st occurrence of regex with replace_str : " );
System.out.println(Str.replaceFirst("geeks", "Akshit"));
}
}
Output
Original String : Welcome to geeksforgeeks After replacing 1st occurrence of regex with replace_str : Welcome to Akshitforgeeks
