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Jul 29th, 2009

Scanner and arraylist of objects

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Hello,

I have a text file that is formatted as such:
Volkswagen, 547, 9.78, 2
Mercedes, 985, 45.77, 35
...

I am trying to figure out how use the Scanner to read from the text file and store the information into an ArrayList of objects.

ArrayList<Car> cars = new ArrayList<Car>();

I would then like to be able to use each element of the arraylist individually. For example:

cars.getName();
cars.getSerial();
...

Here is what I have so far:

Java Syntax (Toggle Plain Text)
 
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
 
public class ScannerTest 
{
    public static void main(String[] args) {
 
       ArrayList<Car> cars = new ArrayList<Car>();
 
        File file = new File("car.csv");       
 
        try {
 
            Scanner scanner = new Scanner(file).useDelimiter(",");
 
            while (scanner.hasNextLine()) 
            {
                String line = scanner.nextLine();
                String name = scanner.next();
                int serial = scanner.nextInt();
                double itemCost = scanner.nextDouble();
                int itemCode = scanner.nextInt();                
 
                System.out.println(name);           
 
 
            }//while
        } //try
        catch (FileNotFoundException e) 
        {
            e.printStackTrace();
        }
 
    }
}
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

public class ScannerTest 
{
    public static void main(String[] args) {

       ArrayList<Car> cars = new ArrayList<Car>();
       
        File file = new File("car.csv");       
        
        try {
           
            Scanner scanner = new Scanner(file).useDelimiter(",");
            
            while (scanner.hasNextLine()) 
            {
                String line = scanner.nextLine();
                String name = scanner.next();
                int serial = scanner.nextInt();
                double itemCost = scanner.nextDouble();
                int itemCode = scanner.nextInt();                
                               
                System.out.println(name);           
               
                
            }//while
        } //try
        catch (FileNotFoundException e) 
        {
            e.printStackTrace();
        }
        
    }
}

For some reason, I am getting a Mismatch input error and the items are not being added to an arraylist for proper usage. Is there a better method to using the file elements individually?

Any assitance will appreciated.
Thank you

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KimJack

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Jul 30th, 2009

Re: Scanner and arraylist of objects

I really hope that someone can provide some suggestions or help to guide me in the right direction.
I am trying to use a scanner to parse a string and use its elements with methods. It is formatted as so:

String line = "Mercedes, 124 124.11, 45";

When I parse the string, I get a java.util.InputMismatchException

here is a snippet:

Java Syntax (Toggle Plain Text)
 Scanner line = new Scanner(line);
                line.useDelimiter(",");
 
                while(line.hasNext())
                {
                	String car = line.next();                	
                	int id = line.nextInt();
                	double serial = line.nextDouble();
                	int code = line.nextInt();         	
                }
 Scanner line = new Scanner(line);
                line.useDelimiter(",");
                
                while(line.hasNext())
                {
                	String car = line.next();                	
                	int id = line.nextInt();
                	double serial = line.nextDouble();
                	int code = line.nextInt();         	
                }

Any suggestions will be a hugely appreciated.

KimJack

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since Apr 2006

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Jul 30th, 2009

Re: Scanner and arraylist of objects

Scanner line = new Scanner(line);
This looks wrong. There is no constructor for Scanner that takes a Scanner as a parameter.

JamesCherrill

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since Apr 2008

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Jul 31st, 2009

Re: Scanner and arraylist of objects

Click to Expand / Collapse Quote originally posted by KimJack ...

I really hope that someone can provide some suggestions or help to guide me in the right direction.
I am trying to use a scanner to parse a string and use its elements with methods. It is formatted as so:

String line = "Mercedes, 124 124.11, 45";

When I parse the string, I get a java.util.InputMismatchException

here is a snippet:
Java Syntax (Toggle Plain Text)
 Scanner line = new Scanner(line);
                line.useDelimiter(",");
 
                while(line.hasNext())
                {
                	String car = line.next();                	
                	int id = line.nextInt();
                	double serial = line.nextDouble();
                	int code = line.nextInt();         	
                }
Scanner line = new Scanner(line); line.useDelimiter(","); while(line.hasNext()) { String car = line.next(); int id = line.nextInt(); double serial = line.nextDouble(); int code = line.nextInt(); }
Any suggestions will be a hugely appreciated.

Hi
In the example above you have named your scanner as line and your string as line. Thats is confusing and makes it difficult for you to search for faults. In the string there is no "," after the id number. Maybe you just missed it writing it down in your post here? If you also missed it in your code you will get an error.

I could be that your .useDelimiter(",*"); works better if you tell it there is a space after the "," like this .useDelimiter(",\\s*");

You probably will get some error trying to catch the serial like this:
double serial = line.nextDouble();
Try like this instead:
String s = new String();
double serial = Double.valueOf(s = line.next());
This way you catch the serial as a string and makes a double out of the value from the string.

I am not really sure of why you have put in inside a while loop but my advise is to take it out of the loop if you have trouble until you catch does results you want and first then put your stuff inside any kind of loop.

Use System.out.println(); to test what you get and how it looks.
I can not see that you are closing your scanner?
You do that in the same way you are closing streams, whit a simple .close();

Hope this will give you some help.
Good luck =)

sneaker

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