How to use regular expressions to match everything before a certain type of word

Question

I am new to regular expressions.

Is it possible to match everything before a word that meets a certain criteria:

E.g.

THIS IS A TEST - - +++ This is a test

I would like it to encounter a word that begins with an uppercase and the next character is lower case. This constitutes a proper word. I would then like to delete everything before that word.

The example above should produce: This is a test

I only want to this processing until it finds the proper word and then stop.

Any help would be appreciated.

Thanks

Answer 1

Replace

^.*?(?=[A-Z][a-z])

with the empty string. This works for ASCII input. For non-ASCII input (Unicode, other languages), different strategies apply.

Explanation

.*?    Everything, until
(?=    followed by
[A-Z]  one of A .. Z and
[a-z]  one of a .. z
)

The Java Unicode-enabled variant would be this:

^.*?(?=\p{Lu}\p{Ll})

Answer 2

Having woken up a bit, you don't need to delete anything, or even create a sub-group - just find the pattern expressed elsewhere in answers. Here's a complete example:

import java.util.regex.*;

public class Test
{
    public static void main(String args[])
    {
        Pattern pattern = Pattern.compile("[A-Z][a-z].*");

        String original = "THIS IS A TEST - - +++ This is a test";
        Matcher match = pattern.matcher(original);
        if (match.find())
        {
            System.out.println(match.group());
        }
        else
        {
            System.out.println("No match");
        }        
    }
}

EDIT: Original answer

This looks like it's doing the right thing:

import java.util.regex.*;

public class Test
{
    public static void main(String args[])
    {
        Pattern pattern = Pattern.compile("^.*?([A-Z][a-z].*)$");

        String original = "THIS IS A TEST - - +++ This is a test";
        String replaced = pattern.matcher(original).replaceAll("$1");

        System.out.println(replaced);
    }
}

Basically the trick is not to ignore everything before the proper word - it's to group everything from the proper word onwards, and replace the whole text with that group.

The above would fail with "*** FOO *** I am fond of peanuts" because the "I" wouldn't be considered a proper word. If you want to fix that, change the [a-z] to [a-z\s] which will allow for whitespace instead of a letter.