Regex extract string, why my pattern don't works?

Question

I have a long string in this format (a long single line in file):

"1":"Aname","2":"AnotherName","3":"Sempronio"

I want to extract the number and the name and save them on a Map.

I tried this:

    FileReader fileReader = null;
    BufferedReader br = null;

    File file = new File("./SingleLineFileNames.txt");
    try {
        fileReader = new FileReader(file);
        br = new BufferedReader(fileReader);

        String line;
        Pattern p = Pattern.compile("\"(\\d+)\":\"([\\w-.' ]+)\"");
        Matcher matcher;
        while((line = br.readLine()) != null) {
            matcher = p.matcher(line);

            String name;
            int i = 1;
            while((name = matcher.group(i)) != null){ 
                // save in map
                i++;
            }

        }

    }
    catch (FileNotFoundException e) {
        e.printStackTrace();
    }
    catch (IOException e) {
        e.printStackTrace();
    }
    finally {
        try {
            br.close();
            fileReader.close();
        }
        catch (IOException e) {
            e.printStackTrace();
        }
    }
    return null;

result is java.lang.IllegalStateException: No match found

It's the right way to iterate on groups?

Where I wrong?

Are you working on JSON? Use a proper parser for that, please. — nhahtdh
– nhahtdh, Commented Mar 7, 2014 at 11:27

Smutje · Accepted Answer · 2014-03-07 11:33:45Z

1

First split the String at , (String#split) and then split each resulting array element at : to get key and value. With input strings like these, I wonder what kind of masochism is on the developers using regex sledgehammers breaking these simple nuts..

answered Mar 7, 2014 at 11:33

Smutje

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1 Comment

d3vnico Over a year ago

I guess that regex is a most elegant way to parse this string.

Sabuj Hassan · Accepted Answer · 2014-03-07 11:27:59Z

0

If you use hyphen inside [] then always place at the first or at the last.

Pattern p = Pattern.compile("\"(\\d+)\":\"([-\\w.' ]+)\"");
                                            ^ here

Also the way you are checking the group() is not correct. Check here:

while(matcher.find()){ 
    System.out.println(matcher.group(1));
    System.out.println(matcher.group(2));
}

answered Mar 7, 2014 at 11:27

Sabuj Hassan

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2 Comments

d3vnico Over a year ago

It works both with Pattern p = Pattern.compile("\"(\\d+)\":\"([\\w-.' ]+)\""); and with Pattern.compile("\"(\\d+)\":\"([-\\w.' ]+)\"");. Why, Sabuj, you say that hypher always place at the first or at the last?

Sabuj Hassan Over a year ago

For example this one [a-z] it means any character from a to z. So placing hyphen at the middle can change it's meaning. So its always a good practice to use it at start of end in the []

Audrius Meškauskas · Accepted Answer · 2014-03-07 11:30:16Z

0

Remove the broken square bracket construct ([\\w-.' ]+) . For the name containing word characters only, it is enough to put (\\w+) there.

answered Mar 7, 2014 at 11:30

Audrius Meškauskas

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1 Comment

d3vnico Over a year ago

names substrings may contain -, ` ` and .

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