Tutorial

How To Remove a Character from a String in Java

Updated on November 9, 2022
    authorauthor

    Pankaj and Andrea Anderson

    How To Remove a Character from a String in Java

    Introduction

    In this article, you’ll learn a few different ways to remove a character from a String object in Java. Although the String class doesn’t have a remove() method, you can use variations of the replace() method and the substring() method to remove characters from strings.

    Note: String objects are immutable, which means that they can’t be changed after they’re created. All of the String class methods described in this article return a new String object and do not change the original object. The type of string you use depends on the requirements of your program. Learn more about other types of string classes and why strings are immutable in Java.

    The String class has the following methods that you can use to replace or remove characters:

    • replace(char oldChar, char newChar): Returns a new String object that replaces all of the occurrences of oldChar in the given string with newChar. You can also use the replace() method, in the format replace(CharSequence target, CharSequence replacement), to return a new String object that replaces a substring in the given string.
    • replaceFirst(String regex, String replacement): Returns a new String object that replaces the first substring that matches the regular expression in the given string with the replacement.
    • replaceAll(String regex, String replacement): Returns a new String object that replaces each substring that matches the regular expression in the given string with the replacement.
    • substring(int start, int end): Returns a new String object that contains a subsequence of characters currently contained in this sequence. The substring begins at the specified start and extends to the character at index end minus 1.

    Notice that the first argument for the replaceAll() and replaceFirst() methods is a regular expression. You can use a regular expression to remove a pattern from a string.

    Note: You need to use double quotes to indicate literal string values when you use the replace() methods. If you use single quotes, then the JRE assumes you’re indicating a character constant and you’ll get an error when you compile the program.

    Remove a Character from a String in Java

    You can remove all instances of a character from a string in Java by using the replace() method to replace the character with an empty string. The following example code removes all of the occurrences of lowercase “a” from the given string:

    String str = "abc ABC 123 abc";
    String strNew = str.replace("a", "");
    
    Output
    bc ABC 123 bc

    Remove Spaces from a String in Java

    You can remove spaces from a string in Java by using the replace() method to replace the spaces with an empty string. The following example code removes all of the spaces from the given string:

    String str = "abc ABC 123 abc";
    String strNew = str.replace(" ", "");
    
    Output
    abcABC123abc

    Remove a Substring from a String in Java

    You can remove only the first occurrence of a character or substring from a string in Java by using the replaceFirst() method to replace the character or substring with an empty string. The following example code removes the first occurrence of “ab” from the given string:

    String str = "abc ABC 123 abc";
    String strNew = str.replaceFirst("ab", "");
    
    Output
    c ABC 123 abc

    Remove all the Lowercase Letters from a String in Java

    You can use a regular expression to remove characters that match a given pattern from a string in Java by using the replace.All() method to replace the characters with an empty string. The following example code removes all of the lowercase letters from the given string:

    String str = "abc ABC 123 abc";
    String strNew = str.replaceAll("([a-z])", "");
    
    Output
    ABC 123

    Remove the Last Character from a String in Java

    There is no specific method to replace or remove the last character from a string, but you can use the String substring() method to truncate the string. The following example code removes the last character from the given string:

    String str = "abc ABC 123 abc";
    String strNew = str.substring(0, str.length()-1);
    
    Output
    abc ABC 123 ab

    Try it out

    The following example file defines a class that includes all of the method examples provided in this article, and prints out the results after invoking each method on the given string. You can use this example code to try it out yourself on different strings using different matching patterns and replacement values.

    If you have Java installed, you can create a new file called JavaStringRemove.java and add the following code to the file:

    JavaStringRemove.java
    
    public class JavaStringRemove {
    
    	public static void main(String[] args) {
        	String str = "abc ABC 123 abc";
    
    		// Remove a character from a string in Java
    		System.out.println("String after removing all the 'a's = "+str.replace("a", ""));
    
    		// Remove spaces from a string in Java
    		System.out.println("String after removing all the spaces = "+str.replace(" ", ""));
    
    		// Remove a substring from a string in Java	
    		System.out.println("String after removing the first 'ab' substring = "+str.replaceFirst("ab", ""));
    
    		// Remove all the lowercase letters from a string in Java
    		System.out.println("String after removing all the lowercase letters = "+str.replaceAll("([a-z])", ""));
    
    		// Remove the last character from a string in Java
    		System.out.println("String after removing the last character = "+str.substring(0, str.length()-1));
    	}
    
    }
    

    Compile and run the program:

    1. javac JavaStringRemove.java
    2. java JavaStringRemove

    You get the following output:

    Output
    String after removing all the 'a's = bc ABC 123 bc String after removing all the spaces = abcABC123abc String after removing the first 'ab' substring = c ABC 123 abc String after removing all the lowercase letters = ABC 123 String after removing the last character = abc ABC 123 ab

    Each method in the JavaStringRemove example class operates on the given string. The output shows that the characters specified in each method have been removed from the string.

    Conclusion

    In this article you learned various ways to remove characters from strings in Java using methods from the String class, including replace(), replaceAll(), replaceFirst(), and substring(). Continue your learning with more Java tutorials.

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    About the authors
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    Pankaj

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    Technical Editor


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    JournalDev
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    April 10, 2020

    tried to replace, just like you show’d but tells me an error: The method replace(char, char) in the type String is not applicable for the arguments (char, String) my code: aNum=aNum.replace(aNum.charAt(i), “”);

    - slava

      JournalDev
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      January 26, 2020

      this is useful

      - Piyush Chavare

        JournalDev
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        February 26, 2019

        I want to replace a few words from a String , Whenever a match will be founded it will remove that match . Example : “Learning java is not so easy but also” /* is not so much hard */ ". All that I need to replace the whole comment section ( /* ----------*/). In this case what I should do ?

        - Indrajit Das

          JournalDev
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          February 26, 2019

          This article will provide good knowledge, who are welling to learn java. . It was great experience. Good platform to enhance our knowledge. I found a clear description in each and every topic.

          - Nisha

            JournalDev
            DigitalOcean Employee
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            February 24, 2019

            how to remove the string of characters from another string eg: “lhe” from “hello world”.

            - abcd

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