Java scanner separating data from an input file

Question

I'm kinda new to java and I'm a little confused at the moment. Im trying to get some input data from a file and the like parse it/ and give it the correct fields for what its equal to. For example,my "in.txt"

Number: 2 Gender: 1 City: 4 Car: 7       
Gender: 1 City: 4 Number: 1                                                                                 
City: 2 Car: 1 Number: 3

I'm trying to get to where Number equals 2 and Gender equals 1, and City equals 4, etc.. So far I'm able to use java's Scanner to read the file so I know that its reading it right. So how would I be able to correspond the names to the numbers like (Number: 2). Should I split the line whenever it sees an ":"? Like give it a left and a right side, or would that mess up the rest of the line with "Gender: 1 City: 4 ..."? I'm trying different things as I'm typing this and I'm just becoming stuck in how I would separate the data from the file. I greatly appreciate any help. Thank you. This is my scanner file I'm using to get the file.

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

public class example{
  public static void main(String[] args) throws FileNotFoundException{
    File inFile = new File("in.txt");
    Scanner input = new Scanner(inFile);
    while(input.hasNext()){
        String line = input.nextLine();
        System.out.println(line);
    }   
  }
}

Answer 1

If your file or the lines are always build like you described it, you can split for spaces and search in the array for your needed value eg "Number:" (if necessary you can remove the ":") and then watch in the array at this position + 1 and there is the value.

Splitting for ":" will end up in such an array:

{[Number],[ 2 Gender],[ 1 City],[ 4 Car],[ 7]}

so I think this is not the best solution.

Answer 2

One way to tackle the problem of identifying each key/value pair in each line would be to use regular expressions to find each pair in a line. The Java Tutorials on Regular Expressions provide a good, and fairly comprehensive, starting point on the topic.

To get you started on this, the regular expression [A-Za-z]+: [0-9]+ will isolate each key-value pair for you, and a regular expression helper such as this web page at regexplanet.com will help greatly with testing and to start to identify the code you would need.

Answer 3

Do you want to get these numbers? 1: If i understand correctly,you could do this.

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Number {   
    public static void main(String[] args) {
        String regex = "\\d+";
        String candidate = "Number: 2 Gender: 1 City: 4 Car: 7  ";

        Pattern p = Pattern.compile(regex);
        Matcher matcher = p.matcher(candidate);
        while(matcher.find()){
            System.out.println(matcher.group());
        }
    }
}

2:if you can format your data,you can format to JSON ,and use json-lib.jar