JAVA parsing data from txt file

Question

I have been attempting to separate values from a text file. The values are not tab separated but varying,and I am trying to put them into different arrays. A sample of the text file is shown below.

1908 1 5.0 -1.4 21 --- 29.7 1908 2 7.3 1.9 8 --- 71.9 1908 3 6.2 0.3 13 --- 101.4 1908 4 8.6 2.1 5 --- 128.6 1908 5 15.8 7.7 0 --- 180.4 1908 6 17.7 8.7 0 --- 196.9 1908 7 18.9 11.0 0 --- 196.1 1908 8 17.5 9.7 0 --- 187.2 1908 9 16.3 8.4 0 --- 99.5 1908 10 14.6 8.0 0 --- 56.1 1908 11 9.6 3.4 6 --- 28.4 1908 12 5.8 0.0 13 --- 10.3 1909 1 5.0 0.1 11 --- 35.6 1909 2 5.5 -0.3 18 --- 49.9 1909 3 5.6 -0.3 17 --- 58.7 1909 4 12.2 3.3 3 --- 188.9 1909 5 14.7 4.8 2 --- 216.8 1909 6 15.0 7.5 0 --- 139.5 1909 7 17.3 10.8 0 --- 151.2 1909 8 18.8 10.7 0 --- 167.5 1909 9 14.5 8.1 0 --- 74.4 1909 10 12.9 6.9 3 --- 101.5

The arrays I am splitting the data into at the moment is just the year; I will then create the code for the remaining sets of data.

The arrays would be like this:

yyyy [0] 1908
     [1] 1908
ect

public class test {
    private static String removeCharacters(String string){
        string = string.replace("*", "");
        string = string.replace("#", "");
        string = string.replace("---", "");
        return string;
    }


    public static void main(String[] args) throws IOException {
        int i = 0;
        double test[]= new double [1200];
        BufferedReader testFile = new BufferedReader(new FileReader("historical_weather_data/sources/bradforddata.txt"));
        String line;

        testFile.readLine();
        testFile.readLine();
        testFile.readLine();
        testFile.readLine();
        testFile.readLine();
        testFile.readLine();
        testFile.readLine();

        while((line = testFile.readLine()) != null) { 
            String splits[] = line.split("  ");
            test[i] = Double.parseDouble(removeCharacters(splits[0]));
            i++;
        }
        for(int h=0;h<test.length;++h){
            System.out.println(test[h]);
        }
    }
}

From this code the following error is produced:

Exception in thread "main" java.lang.NumberFormatException: For input string: "1908   1    5.0    -1.4      21         29.7"
at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:2043)
at sun.misc.FloatingDecimal.parseDouble(FloatingDecimal.java:110)
at java.lang.Double.parseDouble(Double.java:538)
at test.main(test.java:32)

Any help will be very appreciated.

Carefully read your exception, you're rtrying to parse the string "1908 1 5.0 -1.4 21 29.7" as a double, which gives you the error. You're making an error when reading in the .txt file. — Wim De Troyer
– Wim De Troyer, Commented May 9, 2017 at 20:33
it's too long to copy onto here, google drive link to the document - drive.google.com/open?id=0B4YNBcGEuF3hT3JsLURIZUdTdFE — Jamie
– Jamie, Commented May 9, 2017 at 20:53
line.split(" "); replace this with line.split("\t"); Should fix your issue. — Wim De Troyer
– Wim De Troyer, Commented May 9, 2017 at 20:56

Sean Van Gorder · Accepted Answer · 2017-05-09 21:00:23Z

1

Looking at the linked document, the values are not tab-separated, but use varying numbers of spaces. The split method uses regex, so this should work:

String splits[] = line.split(" +");

answered May 9, 2017 at 21:00

Sean Van Gorder

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7 Comments

Jamie Over a year ago

it produces an empty string using that, Exception in thread "main" java.lang.NumberFormatException: empty String

Sean Van Gorder Over a year ago

Try using splits[1]. The lines start with spaces, so the first split is between the start of the line (empty string) and the first number.

Jamie Over a year ago

that's got it! Thank you very much!

Wim De Troyer Over a year ago

@Jamie alternatively, use this String[] newLine = line.trim().split(" +");

Jamie Over a year ago

@SeanVanGorder I've finished all of the program now, thanks for you help, just so I understand for further programs, what did you + sign do?

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