Extract an int from a file using multiple delimiters

Question

I have a text file:

  90,-5 ,, 37  ,  1  99
  0 -55,,,
  ,,,11

I need to extract the integers into an array. I have been traing to do so with this code:

File file=new File("2.txt");
Scanner in=new Scanner(file);
in.useDelimiter(" *|,*|\\n");
int[] b=new int[20];
int i=0;
while(in.hasNextInt()){
  b[i]=in.nextInt();
  i++;  
              }
  in.close();

What i doing wrong?

Answer 1

There is a mismatch between the delimiter expression and the separator characters. In this case, it is simpler to match the characters in which you are interested rather then separator characters. A precompiled Pattern can be used for greater performance.

Pattern pattern = Pattern.compile("-?\\d+");
BufferedReader reader = new BufferedReader(new FileReader("2.txt"));
String line;

while ((line = reader.readLine()) != null) {
    Matcher m = pattern.matcher(line);
    while (m.find()) {
        System.out.println(m.group(0));
    }
}

Answer 2

I think you may need to read the documentation on patterns, because in a quick brush through now it doesn't look like | is the union operator. Also, wouldn't \\\\n be a literal backslash n, not the newline character?

http://docs.oracle.com/javase/tutorial/essential/regex/index.html

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