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

// 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

// 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

// 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