Regex to read specific file format in Java

Question

I need to read a file with this format:

(w,x,y,z),(w,x,y,z), ... ,(w,x,y,z);

All on one line.

//edit:

I eventually will need to do this on files like the following as well:

(w,x,y,z_1 ... z_n),(w,x,y,z_1 ... z_n), ... ,(w,x,y,z_1 ... z_n);

so simply reading past 3 commas is not going to cut it.

My plan is to read the whole file into a String using the Scanner class, then splitting it up in an array of (w,x,y,z) parts and then splitting that up into the actual w, x, y and z. Eventually the data in the file would end up in a list of objects something like:

public class DataBean {
    private String w, x, y, z;
    ...
}

I'm having trouble coming up with a regular expression for this though. I tried

String[] allSystems = scanner.nextLine ( ).split ( "),(" );

and sure, it cuts the string up, but I feel it's not the most elegant solution. If anyone has a better idea I'd love to hear!

Frankly I don't think you're going to find a more elegant solution than that. Elegant != Fancy. String[] allSystems = scanner.nextLine ( ).split ( "),(" ); is a very clean way to do it — StormeHawke
– StormeHawke, Commented Oct 17, 2013 at 19:27

Paul Vargas · Accepted Answer · 2013-10-17 19:36:44Z

3

You can try:

String[] allSystems = scanner.nextLine ( ).split ( "(?<=\\)),(?<!\\()" );

You get (w,x,y,z), (w,x,y,z), (w,x,y,z);

Next, for get w, x, y, z, you can do:

String system = "(w,x,y,z);";

String[] data = system.replaceAll("\\(|\\);?", "").split(",");

answered Oct 17, 2013 at 19:36

Paul Vargas

42.2k16 gold badges108 silver badges148 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Erik Gillespie · Accepted Answer · 2013-10-17 19:43:55Z

1

If you use line.split("(^\\(|\\),\\(|\\);|,)") then you will get a String array with each w, x, y, and z as its own element in the array. The first item in the array will be an empty String, but if you start at index 1 you can easily use this to construct your DataBean objects:

String[] data = line.split("(^\\(|\\),\\(|\\);|,)");

List<DataBean> dataBeans = new ArrayList<DataBean>();
for (int i = 1; i < data.length; i += 4) {
    dataBeans.add(new DataBean(data[i], data[i+1], data[i+2], data[i+3]);
}

answered Oct 17, 2013 at 19:43

Erik Gillespie

3,9792 gold badges34 silver badges48 bronze badges

Collectives™ on Stack Overflow

Regex to read specific file format in Java

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related