Question

I’m trying to use a text file as a database for some data I collect from a user, this is a constructor I’m using

public DatabaseOperations(String name,double newWeight) throws FileNotFoundException, ParseException{
    f= new File (removeSpaces(name)+".txt");
    if (!f.exists()){
        System.out.println("This user dosen't exist");
        return;
    }
    try {
        out= new PrintWriter (f);
    } catch (FileNotFoundException e) {
        System.out.println("Error, You don't say");
    }
    // This section is used to initialize a new object from Customer with values in the excising file
    cust = new Customer();
    in=new Scanner(f);
    in.next();
    in.next();
    cust.setName(in.next());
    in.next();
    in.next();
    in.next();
    cust.setStartingDate(in.next());
    in.next();
    in.next();
    cust.setAge(Integer.parseInt(in.next()));
    in.next();
    in.next();
    in.next();
    cust.setStartingWeight(Double.parseDouble(in.next()));
    in.next();
    in.next();
    cust.setHeight(Double.parseDouble(in.next()));
    in.next();
    in.next();
    in.next();
    cust.setBMI(Double.parseDouble(in.next()));
    in.next();
    in.next();
    in.next();
    cust.setTargetWeight(Double.parseDouble(in.next()));
    in.next();
    in.next();
    in.next();
    cust.setTargetDate(in.next());
    //----------------------------------------------------------------
    // check this for errors !!!
    cust.setWeight(newWeight);
    out.println(form.format(cust.getCurrentDate())+"\t"+df.format(cust.getWeight())+"\t\t"+cust.getBMI()+"\t\t"+cust.percentDone()+"\t"+cust.timePassed());
    out.close();
}

these many in.next() are used to skip some data I don’t need, the structure of the file I’m using is like that

Name :kkkk  Started at :06/12/2012
Age :19 Starting Weight :85.0
Height :1.86        Starting BMI :24.57
Target Weight :75.5 Target Date :15/12/2012

the problem is that the compiler throws a NoSuchElementException and points me to the first (in.next())
another problem is that as soon as I invoke this constructor the file becomes empty !!!

Answer 1

I would highly recommend using the java.util.Properties class if you want to use a text-file instead of a database. No need for using next(), you can solve this with key/value pairs: http://docs.oracle.com/javase/6/docs/api/java/util/Properties.html

Properties prop = new Properties();

try {
  prop.load(new FileInputStream(removeSpaces(name)+".txt"));
  cust.setAge(Integer.parseInt(prop.getProperty("age")));
} catch (IOException e) {
  e.printStackTrace();
}

The properties text-file looks like this

age=19
name=kkkk
started_at=06/12/2012
starting_weight=85.0