Exception in thread "main" java.lang.NumberFormatException: For input string: " "

Question

I am attempting to access two string values within a simulation.log file and convert the two values to a type long. This is an example of the log file:

Log Fille

When I attempt to access the strings it is telling myself the are empty values. The error I am getting is:

Error

My code is as follows (I understand the statement is not fully closed):

File file = new File(simulationLogDir + "/simulation.log");
        FileReader simulationLogReader = new FileReader(file);
        BufferedReader bufferedReader = new BufferedReader(simulationLogReader);
        StringBuffer stringBuffer = new StringBuffer();
        String line;
        while ((line = bufferedReader.readLine()) != null) {
            String[] fields = line.split("\t");
            long responseTime = Long.parseLong(fields[5]) - Long.parseLong(fields[4]);
            if (line.startsWith("REQUEST")) {
                if (fields[7].equals("OK")) {
                    addPassedTest(fields[1], new Request(fields[4],responseTime, fields[7]));
                }

Each line in the simulation log is separated by tabbed spaces so the fields array separates each string.

Please show the log file and the exception in text and not as screenshot — SilverNak, Apr 11 '17 at 17:07
@ammoQ thank you! This was not the problem but it allowed me to figure out that it was reading in a line of the file I had no use for. Thanks for your quick response. — James O'Reilly, Apr 11 '17 at 17:17

score 0 · Answer 1 · edited Jun 20 '20 at 09:12

TO SUMMARIZE:

Double check your file for mistyped spaces.

Based on what I have noticed. Line 8 (Two parseLongs) is really vulnerable to exception, or we can say can throw NumberFormatException especially when it parses non-numerical string.

When does it happen? Based on the title of the question Exception in thread “main” java.lang.NumberFormatException: For input string: “ ”, I'm pretty sure you an instance of a line in your file that has a space right after a tab and coincidentally parsed by a Long.parseInt(string num);

To explain it even further, I'll give you 2 Sample Situations.

SITUATION 1: There is a line in your file that look like this

REQUEST (tab) test_12345_54321 (tab) 1 (tab) Macbook Request (tab) (space) 1490183061440 (tab) 1490183061321 (tab) OK

This line will then be splitted in such manner as follows:

fields[0] = REQUEST
fields[1] = test_12345_54321
fields[2] = 1
fields[3] = Macbook Request
fields[4] = (space) 1490183061440
fields[5] = 1490183061321
fields[6] = OK

Parsing 4th index and fifth index will be:

Long.parseLong(fields[4]) -> space can't be parsed as results to NumberFormatException
Long.parseLong(fields[5]) = 1490183061321 -> works fine

SITUATION 2: There is a line in your file that look like this

REQUEST (tab) test_12345_54321 (tab) 1 (tab) Macbook Request (tab) 1490183061440 (tab) (space) (tab) 1490183061321 (tab) OK

This line will then be splitted in such manner as follows:

fields[0] = REQUEST
fields[1] = test_12345_54321
fields[2] = 1
fields[3] = Macbook Request
fields[4] = 1490183061440
fields[5] = (space)
fields[5] = 1490183061321
fields[6] = OK

Parsing 4th index and fifth index will be:

Long.parseLong(fields[4]) = 1490183061440 -> works fine
Long.parseLong(fields[5]) -> space can't be parsed as results to NumberFormatException

Exception in thread "main" java.lang.NumberFormatException: For input string: " "

1 Answers1

Double check your file for mistyped spaces.