CODEWITHSUNDEEP
javaparsingvector
Matt
Matt

Reputation: 1032

Java - Parse double from file containing double and int

I have the following method in java which reads a file of numbers (tab separated) and puts the numbers in a vector of Doubles

public static Vector<Double> getData(String path,int dataNum) throws Exception
{
    File file = new File(path);
    Scanner scan = new Scanner(file);
    scan.useDelimiter("\t");

    Vector<Double> content = new Vector<Double>();
    int limit = 0;

    while(scan.hasNext() && limit < dataNum)
    {
        content.add(Double.parseDouble(scan.next()));
        limit++;
    }

    return content;
}

This is my sample file

0   20000   -9.2149 1.6078  4.1023  0.0089185   0.0057066   0.015156

However, when i run the code, I get the following error

Exception in thread "main" java.lang.NumberFormatException: For input string: "0
0"
    at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1222)
    at java.lang.Double.parseDouble(Double.java:510)
    at midterm.main.getData(main.java:91)
    at midterm.main.main(main.java:123)

I believe my mistake is that I am parsing double but my file contains 0 and 2000 and that java sees them as integer. But EVEN if they are integers, i want them to be treated as Doubles and still go into my vector.

Upvotes: 1

Views: 1223

Answers (2)

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726569

This is not the entire content of my file. It's a file of 165 MB. MANY lines. but each line, the numbers are tab separated.

The problem is with the delimiter then: you need to allow \n to be a delimiter as well:

scan.useDelimiter("[\t\n]");

Otherwise, the last number of the first line and the first number from the second line would be bunched together into a single string that looks like this: "0\n0" and prints like two zeros on different lines, matching the error message that you get.

Demo.

Upvotes: 3

Mike &#39;Pomax&#39; Kamermans
Mike &#39;Pomax&#39; Kamermans

Reputation: 53598

Instead of a scanner, just read the entire line in, split it on "\t" and then run through the resulting String[] with a "for-each" style for loop?

import java.util.*;
public class Test {
  public static void main(String[] args) {
    String input = "0\t20000\t-9.2149\t1.6078\t4.1023\t0.0089185\t0.0057066\t0.015156";
    String[] columns = input.split("\t");
    Vector<Double> dv = new Vector<Double>();
    for(String s: columns) {
      dv.add(Double.parseDouble(s));
    }
    System.out.println(dv.toString());
  }
}

Output:

[0.0, 20000.0, -9.2149, 1.6078, 4.1023, 0.0089185, 0.0057066, 0.015156]

Upvotes: 0

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