Remove last set of value from a comma separated string in java

I wan to remove the last set of data from string using java. For example I have a string like A,B,C, and I want to remove ,C, and want to get the out put value like A,B . How is it possible开发者_开发问答 in java? Please help.

String start = "A,B,C,";
String result = start.subString(0, start.lastIndexOf(',', start.lastIndexOf(',') - 1));

Here is a fairly "robust" reg-exp solution:

Pattern p = Pattern.compile("((\\w,?)+),\\w+,?");

for (String test : new String[] {"A,B,C", "A,B", "A,B,C,",
                                 "ABC,DEF,GHI,JKL"}) {
    Matcher m = p.matcher(test);
    if (m.matches())
        System.out.println(m.group(1));
}

Output:

A,B
A
A,B
ABC,DEF,GHI

Since there may be a trailing comma, something like this (using org.apache.commons.lang.StringUtils):

ArrayList<String> list = new ArrayList(Arrays.asList(myString.split()));
list.remove(list.length-1);
myString = StringUtils.join(list, ",");

You can use String#lastIndexOf to find the index of the second-to-last comma, and then String#substring to extract just the part before it. Since your sample data ends with a ",", you'll need to use the version of String#lastIndexOf that accepts a starting point and have it skip the last character (e.g., feed in the string's length minus 1).

I wasn't going to post actual code on the theory better to teach a man to fish, but as everyone else is:

String data = "A,B,C,";
String shortened = data.substring(0, data.lastIndexOf(',', data.length() - 2));

You can use regex to do this

String start = "A,B,C,";
String result = start.replaceAll(",[^,]*,$", "");
System.out.println(result);

prints

A,B

This simply erases the the 'second last comma followed by data followed by last comma'

If full String.split() is not possible, the how about just scanning the string for comma and stop after reaching 2nd, without including it in final answer?

String start = "A,B";
StringBuilder result = new StringBuilder();
int count = 0;
for(char ch:start.toCharArray()) {
    if(ch == ',') {
        count++;
        if(count==2) {
            break;
        }
    }
    result.append(ch);
}
System.out.println("Result = "+result.toString());

Simple trick, but should be efficient.

In case you want last set of data removed, irrespective of how much you want to read, then start.substring(0, start.lastIndexOf(',', start.lastIndexOf(',')-1))

Another way to do this is using a StringTokenizer:

  String input = "A,B,C,";
  StringTokenizer tokenizer = new StringTokenizer(input, ",");
  String output = new String();
  int tokenCount = tokenizer.countTokens();
  for (int i = 0; i < tokenCount - 1; i++) {
    output += tokenizer.nextToken();
    if (i < tokenCount - 1) {
      output += ",";
    }
  }

public string RemoveLastSepratorFromString(string input)
{
    string result = input;
    if (result.Length > 1)
    {
        result = input.Remove(input.Length - 1, 1);
    }
    
    return result;
}
        
// use from above method
string test = "1,2,3,"
string strResult = RemoveLastSepratorFromString(test);
//output --> 1,2,3