Question

How can I have a text file (or XML file) represented as a whole string, and search for (or match) a particular string in it?

I have created a BufferedReader object:

BufferedReader input =  new BufferedReader(new FileReader(aFile));

and then I have tried to use the Scanner class with its option to specify different delimiters, like this:

//Scanner scantext = new Scanner(input);
//Scanner scantext = new Scanner(input).useDelimiter("");
Scanner scantext = new Scanner(input).useDelimiter("\n");
while (scantext.hasNext()) {  ... }

Using the Scanner class like this I can either read the text line by line, or word by word, but it doesn’t help me, because sometimes in the text, which I want to process, I have

</review><review>

and I would like to say: if you find “<review>” anywhere in the text, do something with the following next lines (or piece of text) until you find “</review>“. The problem is that <review> and </review> are on different places in the text, and sometimes glued to other text (therefore the empty space as delimiter doesn’t help me).

I have thought that I might use the regular expression API in Java (the Pattern and Matcher classes), but they seem to match a particular string or line, and I want to have the text as one continuous string (at least this was my impressions from what I have read about them). Could you tell me what structures/methods/classes I should use in this case? Thank you.

Answer 1

Don’t try to parse XML with regular expressions; it leads only to pain. There are a lot of very nice existing XML APIs in Java already; why try to reinvent them?

Anyway, to search for a string in a text file, you should:

1. Load the file as a string (example)
2. Create a Pattern to search for
3. Use a Matcher to iterate through any matches