Java Replace Char in String

Replacing a character in a string refers to placing another character at the place of the specified character.  An index represents specified characters. In java, the String class is used to replace the character & strings. A string is the class of java.lang packages.

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In programming, developers face many situations where they have to need to replace characters in the string. Java provides multiple methods to replace the characters in the String. Remove is one of the important methods used in replacing the characters. while using the remove method, a few things should be remember

1. String in Java is immutable, so after replacing the character, a new string is created.
2. The string variable before applying the replace method remains the same after applying the replace method.
3. Replace method replaces all the characters in the string with the new character.

Syntax:

 In the following syntax, it is given how a character is being replaced. There are two parameters in the replace method: the first parameter is the character to replace & the second one is the character to be replaced with.

String replace(char oldChar, char newChar):
//OR
String replaceFirst(char oldChar, char newChar):
//replaces only the first occurrence of the character

In the second line of syntax, the replaceFirst method is used to replace only the character’s first occurrence.

Examples of Java Replace Char in String

Below are the examples of Java Replace Char in String:

Example #1

In this example, we can see how a character in the string is replaced with another one.

1. In the first line taking input from the user as a string.
2. Further asking character as an input to replace in the provided string.
3. The replace method creates a new string with the replaced character in the next line because the string in java is immutable.

Code:

import java.util.*;
public class JavaReplaceCharExample{
public static void main(String[] args){
Scanner input = new Scanner(System.in);
System.out.println("Hi, please enter the String");
String str = input.nextLine();
System.out.println("Enter the character to replace");
char ch = input.next().charAt(0);
System.out.println("Enter the character to be replaced with");
char newCh = input.next().charAt(0);
String newStr = str.replace(ch, newCh);
//displaying new string after applying replace method
System.out.println(newStr);
}
}

Output:

Example #2

In this example, replaceFirst is used to only replace the first occurrence of the character in this string.

Code:

import java.util.*;
public class JavaReplaceCharExample2{
public static void main(String[] args){
//second string to replace the character
String str = "All that glitters is not gold";
//displaying string before applying replace method
System.out.println("\n" + str);
//replacing character p from b
String newStr = str.replace("g", "b");
//displaying string after replacing the character
System.out.println(newStr);
//second string to replace the character
String sentence = "A cat has nine lives";
//displaying string before applying replace method
System.out.println("\n" + sentence);
//replacing character n from m
String newSentence = sentence.replaceFirst("n", "m");
//displaying new string after applying replace method
System.out.println(newSentence);
}
}

Output:

The output of the program is given below. In the output screenshot, the first sentence character “g” is replaced by “b”. In the second sentence, only the first occurrence of the syntax “n” is replaced with “m”.

Example #3

In this example,  first replacing a pipe separated value with the comma. After replacing ‘|’ to “,”, in the next line replacing the “A” character to “i” using the replace method.

Code:

import java.util.*;
public class JavaReplaceCharExample3{
public static void main(String[] args){
//second string to replace the character
String str = "Alabama|California|Florida|Texas|New Jersey|Arizona";
//displaying string before applying replace method
System.out.println("\n" + str);
//replacing | with the comma
String newStr = str.replace('|', ',');
//displaying string after applying replace method
System.out.println("\n" + newStr);
//replacing the character A with the i
String reNewedStr = newStr.replace('A', 'i');
//displaying string before applying replace method
System.out.println("\n" + reNewedStr);
}
}

Output:

Example #4

In this example, we can see how a string can be replaced without using the replace method. The string before & after the specified character is stored in a separate variable in the below-given program. Further in the program, it is concatenated with the character to be replaced with.

Code:

import java.util.*;
public class JavaReplaceCharExample4{
public static void main(String[] args){
//second string to replace the character
String str = "Be slow in choosing, but slower in changing.";
//displaying string before applying replace method
System.out.println("\n" + str);
int index = 3;
char chToReplacedWith = 'b';
String strBeforeChar = str.substring(0, index);
String strAfterChar  = str.substring(index + 1);
String newStr  = strBeforeChar + chToReplacedWith + strAfterChar;
//displaying string before applying replace method
System.out.println("\n" + newStr);
}
}

Output:

Conclusion

The above-given article describes how to replace char in a string, what methods are provided by java packages to work with the string. In the given examples, it is given how string class methods can be used to replace characters in a string.

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