splitting string from csv

[Carolin Sha]

Hi,

I am trying to split the strings into components, put each token into appropriate variables, convert where necessary to integer and construct an object.
Please see my code below where I am editing the parseBook() method. Any help would be appreciated. I keep getting null as the output. For the output I would like to get the data separated as:
title: xxxx
author:xxx
publisher:xxxx

etc

import java.io.FileInputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;


public class BookCSVParser {

	public static List<Book> parseBookChart(String filename) {
		Scanner in = getScanner(filename);
		if(in == null) {
			return null;
		}
		List<Book> books = new ArrayList<Book>();
		while(in.hasNextLine()) {
			String line = in.nextLine();
			Book book = parseBook(line);
			books.add(book);
		}
		in.close();
		return books;
	}

	private static Scanner getScanner(String filename) {
		Scanner in = null;

		try {
			in = new Scanner(new FileInputStream(filename), "UTF-8");
		} catch (IOException e) {
			System.err.println("File "+filename+" does not exist.");
			return null;
		}
		//two non-book lines to skip:
		in.nextLine();
		in.nextLine();

		return in;
	}

	private static Book parseBook(String line) {

	 String str1= "Everyday Super Food; Jamie Oliver ; Michael Joseph ;Food & Drink; 0718181239; 2015; 312; 71140";
	 String names1[] = str1.split(";");

     String title = token[0];
     String author = token[1];
     String publisher = token[2];
     String genre = token[3];
     Int isbn = token[4];
     Int yop = token[5];
     Int numberofpages = token[6];
     Int totalsales = token[7];

	 for(String val : names1)
	 System.out.println(val);

     String str2= "My Story;  Steven Gerrard; Penguin; Biography ; 1405923385;2015;496; 77231";
	 String names2[] = str2.split(";");

	 for(String val : names2)
	 System.out.println(val);

     String str3= "The Girl on the Train; Paula Hawkins; Doubleday ;Crime, Thrillers & Mystery; 0857522310; 2015; 320; 57168";
	 String names3[] = str3.split(";");

	 for(String val : names3)
	 System.out.println(val);

     Book b = new Book(title,author,publisher,genre,isbn,yop,numberofpages,totalsales);

     return b;

	}


	public static void main(String[] args) {

		List<Book> books = BookCSVParser.parseBookChart("books.csv");
		for(Book b : books) {
			System.out.println(b);
		}
	}
}

[Ron McLeod]

The code that you have posted will not compile. so the result you are seeing are not from this code - maybe from some previous version which did compile.

[Liutauras Vilda]

1. Look at line 46. Probably you want to have there names1[0] as well as with others.

2. And what data type is "Int isbn = token[4];"?
Even if data type you were get right, that wouldn't work, as you get strings in your array after you split, so you'd need to parse them to integers. Read about method parseInt to see if it is suitable for you.

[Fred Kleinschmidt]

You use ";" as the regex for split(). This will leave extraneous leading and/or trailing blank characters in your split strings You should use

 " *; *" 

instead.

[Carey Brown]

Try
new Scanner( new File( filename ) )

Edit: never mind

[Carolin Sha]

Please see my updated code.

import java.io.FileInputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;


public class BookCSVParser {

	public static List<Book> parseBookChart(String filename) {
		Scanner in = getScanner(filename);
		if(in == null) {
			return null;
		}
		List<Book> books = new ArrayList<Book>();
		while(in.hasNextLine()) {
			String line = in.nextLine();
			Book book = parseBook(line);
			books.add(book);
		}
		in.close();
		return books;
	}

	private static Scanner getScanner(String filename) {
		Scanner in = null;

		try {
			in = new Scanner(new FileInputStream(filename), "UTF-8");
		} catch (IOException e) {
			System.err.println("File "+filename+" does not exist.");
			return null;
		}
		//two non-book lines to skip:
		in.nextLine();
		in.nextLine();

		return in;
	}

	private static Book parseBook(String line) {

	 String str1= "Everyday Super Food; Jamie Oliver ; Michael Joseph ;Food & Drink; 0718181239; 2015; 312; 71140";
	 String names1[] = str1.split(" *; *");

     String title = names1[0];
     String author = names1[1];
     String publisher = names1[2];
     String genre = names1[3];
     String isbn = names1[4];
     int num1 = Integer.parseInt(isbn);
     String yop = names1[5];
     int num2 = Integer.parseInt(yop);
     String numberofpages = names1[6];
     int num3 = Integer.parseInt(numberofpages);
     String totalsales = names1[7];
     int num4 = Integer.parseInt(totalsales);

	 for(String val : names1)
	 System.out.println(val);

     String str2= "My Story;  Steven Gerrard; Penguin; Biography ; 1405923385;2015;496; 77231";
	 String names2[] = str2.split(" *; *");

	 for(String val : names2)
	 System.out.println(val);

     String str3= "The Girl on the Train; Paula Hawkins; Doubleday ;Crime, Thrillers & Mystery; 0857522310; 2015; 320; 57168";
	 String names3[] = str3.split(";");

	 for(String val : names3)
	 System.out.println(val);

     Book b = new Book(title,author,publisher,genre,isbn,yop,numberofpages,totalsales);

     return b;

	}


	public static void main(String[] args) {

		List<Book> books = BookCSVParser.parseBookChart("books.csv");
		for(Book b : books) {
			System.out.println(b);
		}
	}
}

when I compile getting:
constructor Book in class Book cannot be applied to given types;
Book b = new Book(title,author,publisher,genre,isbn,yop,numberofpages,totalsales);
^
required: String,String,ISBN,String,String,int,BookLength
found: String,String,String,String,String,String,String,String
reason: actual and formal argument lists differ in length
1 error

Process completed.

and when I run getting:
null
null
null
null
null
null
null
null
null
null
null

Process completed.

[Carey Brown]

Arguments being passed in to the Book constructor are of the wrong type and are in the wrong order.

[Knute Snortum]

Fred Kleinschmidt wrote:You use ";" as the regex for split(). This will leave extraneous leading and/or trailing blank characters in your split strings You should use

 " *; *" 

instead.

...or slightly better:

"\\s*;\\s*"

[Anurag Verma]

Try matching the parameters of constructor of Book class, also for splitting why not give a try to StringTokenizer?

[Winston Gutkowski]

Carolin Sha wrote:I am trying to split the strings into components, put each token into appropriate variables, convert where necessary to integer and construct an object.
Please see my code below where I am editing the parseBook() method. Any help would be appreciated.

A couple of things I see:
1. parseBook() should be a method of your Book class - after all, that is the object that "knows" what it looks like.

2. You might also want a "checker" method that makes sure a line can be parsed as a Book, for example:

private static final String[] bookFields(String line) {
   String[] fields = line.split("\\s+;\\s+");
   boolean isValid = fields.length >= 8;
   // Check that fields 4-7 are numeric
   for (int i = 4; isValid && i < 8; i++) {
      isValid &= fields[i].matches("[0-9]+");
   }
   return Arrays.copyOf( fields, (isValid ? 8 : 0) );
}

and then your parseBook() method can be something like:

private static Book parseBook(String line) {
   String[] fields = bookFields(line);
   if (fields.length == 0)
      return null; // or throw an Exception
   // Extract the values for your new Book
   // instance, and return it.
}

HIH

Winston

[Edit] corrected mistake at line 6 of first snippet.

[Dave Tolls]

Anurag Verma wrote:Try matching the parameters of constructor of Book class, also for splitting why not give a try to StringTokenizer?

Quoting from the API for StringTokenizer:
"
StringTokenizer is a legacy class that is retained for compatibility reasons although its use is discouraged in new code. It is recommended that anyone seeking this functionality use the split method of String or the java.util.regex package instead.
"
It's been essentially deprecated for quite a while now.

[Anurag Verma]

Thanks Dave, I didn't knew that.