java regular expression get substring

Question

I can't find any good resource for parsing with regular expression. Could someone please show me the way.

How can I parse this statement?

"Breakpoint 10, main () at file.c:10"

I want get the substring "main ()" or 3rd word of the statement.

Answer 1

This works:

public void test1() {
    String text = "Breakpoint 10, main () at file.c:10";
    String regex = ",(.*) at";

    Pattern pattern = Pattern.compile(regex);
    Matcher matcher = pattern.matcher(text);

    while (matcher.find()) {
        System.out.println(matcher.group(1));
    }
}

Basically the regular expression .(.*) at with group(1) returns the value main () .

Answer 2

Assuming you want the 3rd word of your string (as said in your comments), first break it using a StringTokenizer . That will allow you to specify separator (space is by default)

List<String> words = new ArrayList<String>();
String str = "Breakpoint 10, main () at file.c:10";
StringTokenizer st = new StringTokenizer(str); // space by default

while(st.hasMoreElements()){
    words.add(st.nextToken());
}

String result = words.get(2);

That returns main If you also want the () , as you defined spaces as separator, you also need to take the next word words.get(3)

Answer 3

Have you seen the standard Sun tutorial on regular expressions ? In particular the section on matching groups would be of use.

Answer 4

1. Good website regular-expressions.info
2. Good online tester regexpal.com
3. Java http://download.oracle.com/javase/tutorial/essential/regex/

I turn to these when I want to play with Regex

Answer 5

尝试： .*Breakpoint \\d+, (.*) at

Answer 6

Well, the regular expression main \\(\\) does parse this. However, I suspect that you would like everything after the first comman and before the last "at": ,(.*) at gives you that in group(1) that is opened by the parenthesis in the expression.