javanullpointer by reading from a file while using scanner, bufferedreader and filereader

Question

I'm new to Java programming. I use java to write simple macros for my simulation tool. In the following part of the code I want to find a minimum and a maximum value in a csv file which is "whitespace" seperated.

Now, I have the problem that I get the java.lang.NullPointerException message on my output- window. Than it says that the macro playing is done.

I have some marker in the code and the output ends on this position.

Does anybody have the clue why this not work?

public void VelMinandMax (String Velocity_Data) {

velMagMax = 0.0 ; 
velMagMin = 100.0 ;

FileReader fr1 = null ;
BufferedReader br1 = null ;
Scanner sc1 = null ;

try {
    fr1 = new FileReader(Velocity_Data);
    br1 = new BufferedReader(fr1);
    sc1 = new Scanner(br1); 

    while (sc1.hasNextLine()) {
        sc1.nextLine(); 

        if (sc1.hasNextDouble()) {
            double velMag = sc1.nextDouble();
            double coordX = sc1.nextDouble();
            double coordY = sc1.nextDouble();
            double coordZ = sc1.nextDouble(); 

            if (velMag>velMagMax)
                {
                velMagMax = velMag ;

                }
            if (velMag<velMagMin) 
                {
                velMagMin = velMag ; 

                }
        }
    }   
}
catch (FileNotFoundException e) {
    System.out.println ("Error : File Not Found") ;
}
finally {
    sc1.close() ;
    try {
        br1.close() ;
        fr1.close() ;

        }
    catch (IOException e2)  {
        System.out.println ("IOException"); 
        }
    }
}

Edit Output:

public execute MethodVol CalcVelRef VelMinandMax java.lang.NullPointerException

oky, thanks for reply, i check this up. – Michael Gödeke Oct 23 '17 at 10:18 — Michael Gödeke, Oct 23 '17 at 10:18
Please include the console output. – Cardinal System Oct 23 '17 at 10:19 — Cardinal System, Oct 23 '17 at 10:19

score 0 · Answer 1 · answered Oct 23 '17 at 10:19

0

Don't you pass null in variable Velocity_Data ? That's the only place which can trigger NPE (IMHO).

answered Oct 23 '17 at 10:19

Oleg Gritsak

548
7
26

yeah, i looked up the csv file, one value is null. Can I avoid the error? – Michael Gödeke Oct 23 '17 at 10:36

javanullpointer by reading from a file while using scanner, bufferedreader and filereader

1 Answers1