正则表达式与特殊字符组匹配

Question

I have a String that is something like this:

A20130122.0000+0000-0015+0000_name

Then I would like to extract this information:

The 20130122.0000+0000-0015+0000 that will be parsed to a date later on. And the final part which is name .

So I am using in Java something like this:

String regexpOfdate = "[0-9]{8}\\.[0-9]{4}\\+[0-9]{4}-[0-9]{4}\\+[0-9]{4}";
String regexpOfName = "\\w+";
Pattern p = Pattern.compile(String.format("A(%s)_(%s)", regexpOfdate, regexpOfName));
Matcher m = p.matcher(theString);
String date = m.group(0);
String name = m.group(1);

But I am getting a java.lang.IllegalStateException: No match found

Do you know what I am doing wrong?

Answer 1

You aren't calling Matcher#find or Matcher#matches methods after this line:

Matcher m = p.matcher(theString);

Try this code:

Matcher m = p.matcher(theString);
if (m.find()) {
    String date = m.group(1);
    String name = m.group(2);
    System.out.println("Date: " + date + ", name: " + name);
}

Answer 2

Matcher#group will throw IllegalStateException if the matcher's regex hasn't yet been applied to its target text, or if the previous application was not successful.

Matcher#find applies the matcher's regex to the current region of the matcher's target text, returning a Boolean indicating whether a match is found.

Refer

You can try this :

    String theString="A20130122.0000+0000-0015+0000_name";
    String regexpOfdate = "([0-9]{8})\\.[0-9]{4}\\+[0-9]{4}-[0-9]{4}\\+[0-9]{4}";
    String regexpOfName = "(\\w+)";
    Pattern p = Pattern.compile(String.format("A(%s)_(%s)", regexpOfdate, regexpOfName));
    Matcher m = p.matcher(theString);
    if(m.find()){
      String date = m.group(2);
      String name = m.group(3);
      System.out.println("date: "+date);
      System.out.println("name: "+name);
    }

OUTPUT

date: 20130122
name: name

Refer Grouping in REGEX