CODEWITHSUNDEEP
javastringinteger
Zachery Misson
Zachery Misson

Reputation: 80

Can't change String to Integer because negative sign follows number

I am using Java to read in a CSV file and do some data analysis with the items given. A couple of the data points that I read in are a bunch of different numbers that can range from -999 to 999. I want to compare these numbers to each other so I start by turning the String into an Integer. The problem I get is that the CSV file saves negative numbers with the negative sign following the number (1-). This throws a NullFormatException. I feel like there is an easy way around this that I'm overlooking. Any help would be great.

Say random data is {1,19-,20-,7,8} I need {1,-19,-20,7,8}

int[] nnaOH = new int[x];
int[] nwOH = new int[x];
int[] nuaOH = new int[x];
for (int z = 1; z < x; z++){
    nnaOH[z] = Integer.parseInt(naOH[z]);
    nwOH[z] = Integer.parseInt(wOH[z]);
    nuaOH[z] = Integer.parseInt(uaOH[z]);
    }

Upvotes: 0

Views: 80

Answers (2)

Lars Gendner
Lars Gendner

Reputation: 1982

You can use DecimalFormat to parse your integers with a custom format:

import java.text.DecimalFormat;
import java.text.ParseException;

public class DecimalFormatTest {

    public static void main(String[] args) throws ParseException {
        DecimalFormat decimalFormat = new DecimalFormat("#;#-");
        System.out.println(decimalFormat.parse("123-").intValue());
        System.out.println(decimalFormat.parse("321").intValue());
    }
}

Output:

-123
321

Upvotes: 2

Ben M.
Ben M.

Reputation: 2410

Try something like this. It will detect the hyphen at the end and remove it before parsing the number, setting it to a negative value.

private int parseInt(String str) {

    if (str.endsWith("-")) {
        str = str.substring(0, str.length() - 1);
        return -Integer.parseInt(str);
    } else {
        return Integer.parseInt(str);
    }
}

Upvotes: 0

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