Java

Scanner and arraylist of objects

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Join Date: Apr 2006

Posts: 114

Reputation: KimJack is an unknown quantity at this point

Solved Threads: 0

KimJack

Offline

Junior Poster

Scanner and arraylist of objects

Jul 29th, 2009

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:

 Help with Code Tags 
 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

•

Join Date: Apr 2006

Posts: 114

Reputation: KimJack is an unknown quantity at this point

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KimJack

Offline

Junior Poster

Re: Scanner and arraylist of objects

Jul 30th, 2009

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:

 Help with Code Tags 
 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.

•

Join Date: Apr 2008

Posts: 1,030

Reputation: JamesCherrill is just really nice

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JamesCherrill JamesCherrill is offline

Offline

Veteran Poster

Re: Scanner and arraylist of objects

Jul 30th, 2009

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

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Join Date: Jul 2009

Posts: 48

Reputation: sneaker is an unknown quantity at this point

Solved Threads: 7

sneaker

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Light Poster

Re: Scanner and arraylist of objects

Jul 31st, 2009

•

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:
Help with Code Tags

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 =)