Finding substring using regular exp

I have a string

abc.xyz.qweweer.cccc

This is actually going to be a Java package name.

I am trying to find out the last string using reg exp, in the above example cccc is the last St开发者_开发技巧ring.

Basically I am trying to find out the class name from the package string.

How to find out through Java

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Given a string pkg = "abc.xyz.qweweer.cccc" you can solve it like this:

• Using indexOf:

  int index = pkg.lastIndexOf('.');
  String lastPart = index == -1 ? pkg : pkg.substring(index + 1);
  

• Using regular expressions with Matcher:

  Matcher m = Pattern.compile("[^.]*$").matcher(pkg);
  String lastPart = m.find() ? m.group() : null;
  

• Using split (variation of RMT's answer):

  String[] names = pkg.split("\\.");
  String lastPart = names[names.length - 1];
  

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Why not just split on the "."

String[] names = packageName.split(".");
String className = names[names.length-1];

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Do you really want to use regex? You could do a str.substring (str.lastIndexOf (".") + 1) to get the classname.

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Alt1 - Extract desired

String packageName = ...
Matcher m = Pattern.compile("[a-zA-Z]+$").matcher(packageName);
if (m.find()) {
    m.group(); // your match
}

Alt2 - Remove undesired

You could also try the somewhat less verbose approach:

String result = packageName.replaceAll(".*\\.", "");

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You can use Apache StringUtils substringAfterLast for this.

StringUtils.substringAfterLast("abc.xyz.qweweer.cccc", ".")

Regex is not required for this.