Remove trailing comma from comma-separated string

Question

I got String from the database which have multiple commas (,) . I want to remove the last comma but I can't really find a simple way of doing it.

What I have: kushalhs, mayurvm, narendrabz,

What I want: kushalhs, mayurvm, narendrabz

Answer 1

To remove the ", " part which is immediately followed by end of string, you can do:

str = str.replaceAll(", $", "");

This handles the empty list (empty string) gracefully, as opposed to lastIndexOf / substring solutions which requires special treatment of such case.

Example code:

String str = "kushalhs, mayurvm, narendrabz, ";
str = str.replaceAll(", $", "");
System.out.println(str);  // prints "kushalhs, mayurvm, narendrabz"

---

NOTE: Since there has been some comments and suggested edits about the ", $" part: The expression should match the trailing part that you want to remove.

• If your input looks like "a,b,c,", use ",$".
• If your input looks like "a, b, c, ", use ", $".
• If your input looks like "a , b , c , ", use " , $".

I think you get the point.

Answer 2

You can use this:

String abc = "kushalhs , mayurvm , narendrabz ,";
String a = abc.substring(0, abc.lastIndexOf(","));

Answer 3

Use Guava to normalize all your commas. Split the string up around the commas, throw out the empties, and connect it all back together. Two calls. No loops. Works the first time:

import com.google.common.base.Joiner;
import com.google.common.base.Splitter;

public class TestClass {

    Splitter splitter = Splitter.on(',').omitEmptyStrings().trimResults();
    Joiner joiner = Joiner.on(',').skipNulls();

    public String cleanUpCommas(String string) {
        return joiner.join(splitter.split(string));
    }

}



public class TestMain {

    public static void main(String[] args) {
        TestClass testClass = new TestClass();

        System.out.println(testClass.cleanUpCommas("a,b,c,d,e"));
        System.out.println(testClass.cleanUpCommas("a,b,c,d,e,,,,,"));
        System.out.println(testClass.cleanUpCommas("a,b,,, ,c,d,  ,,e,,,,,"));
        System.out.println(testClass.cleanUpCommas("a,b,c,d,  e,,,,,"));
        System.out.println(testClass.cleanUpCommas(",,, ,,,,a,b,c,d,  e,,,,,"));
    }

}

Output:

a,b,c,d,e
a,b,c,d,e
a,b,c,d,e
a,b,c,d,e
a,b,c,d,e

Personally, I hate futzing around with counting limits of substrings and all that nonsense.

Answer 4

I'm late on this thread but hope it will help to some one.......

String abc = "kushalhs , mayurvm , narendrabz ,";

if(abc.indexOf(",") != -1){
    abc = abc.substring(0,abc.length() - 1);
}

Answer 5

For more than one commas

            String names = "Hello,World,,,";
    System.out.println(names.replaceAll("(,)*$", ""));

Output: Hello,World

Answer 6

(^(\s*?\,+)+\s?)|(^\s+)|(\s+$)|((\s*?\,+)+\s?$)

Regexr

ex:

a, b, c
, ,a, b, c, 
,a, b, c   ,
,,a, b, c, ,,,
, a, b, c,    ,
    a, b, c     
     a, b, c ,,
, a, b, c, 
, ,a, b, c, ,
 , a, b, c , 
,,, a, b, c,,, 
,,, ,,,a, b, c,,, ,,,
,,, ,,, a, b, c,,, ,,,
 ,,,a, b, c ,,,
 ,,,a, b, c,,, 
   a, b, c   

becomes:

a, b, c
a, b, c
a, b, c
a, b, c
a, b, c
a, b, c
a, b, c
a, b, c
a, b, c
a, b, c
a, b, c
a, b, c
a, b, c
a, b, c
a, b, c
a, b, c

Answer 7

And one more ... this also cleans internal commas mixed with whitespace:

From , , , ,one,,, , ,two three, , , ,,four, , , , , to one,two three, four

text.replaceAll("^(,|\\s)*|(,|\\s)*$", "").replaceAll("(\\,\\s*)+", ",");

Answer 8

You can do something like using join function of String class.

import java.util.Arrays;
import java.util.List;

public class Demo {

    public static void main(String[] args) {
        List<String> items = Arrays.asList("Java", "Ruby", "Python", "C++");
        String output = String.join(",", items);
        System.out.println(output);
    }

}

Answer 9

Check if str.charAt(str.length() -1) == ','. Then do str = str.substring(0, str.length()-1)

Answer 10

This method is in BalusC's StringUtil class. his blog

i use it very often and will trim any string of any value:

/**
 * Trim the given string with the given trim value.
 * @param string The string to be trimmed.
 * @param trim The value to trim the given string off.
 * @return The trimmed string.
 */
public static String trim(String string, String trim) {
    if (string == null) {
        return null;
    }

    if (trim.length() == 0) {
        return string;
    }

    int start = 0;
    int end = string.length();
    int length = trim.length();

    while (start + length <= end && string.substring(
            start, start + length).equals(trim)) {
        start += length;
    }
    while (start + length <= end && string.substring(
            end - length, end).equals(trim)) {
        end -= length;
    }

    return string.substring(start, end);
}

ex:

trim("1, 2, 3, ", ", ");

Answer 11

    String str = "kushalhs , mayurvm , narendrabz ,";
    System.out.println(str.replaceAll(",([^,]*)$", "$1"));