Readline(); doesn't work here

Question

1.00/5 (1 vote)

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import java.io.File;
import java.io.FileReader;
import java.util.Scanner;

public class Test {
	
	public static void main ( String[] args) {
		
		Scanner input = new Scanner(System.in);
		System.out.println("Enter name of input file: ");
		String fileName = input.nextLine();
	
		
		String text = " ";
		String line = fileName.readLine();
		while ( line != null)
		{
			text += line ;
			line = fileName.readLine();
		}
		
		System.out.print(text);
	}

}

What I have tried:

it says String doesn't have function called readLine()

Posted 1-Dec-17 11:18am

Member 13552607

Updated 1-Dec-17 11:45am

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Dave Kreskowiak · Answer 1 · 2017-12-01T11:45:00

Solution 1

That's because "filename" is defined as a String. You don't do a file operation on a filename. In your case, you use the filename to open a FileInputStream. You then can call readline() on that stream.

Go through this tutorial[^] because you're going to have to rewrite your code a little bit.

Posted 1-Dec-17 11:45am

Dave Kreskowiak

Comments

PIEBALDconsult 1-Dec-17 18:49pm

"You don't do a file operation on a filename."

Except with an Extension Method in C#. :cool:

Dave Kreskowiak 1-Dec-17 19:46pm

+10 points for you! I like the concept. A little work up front makes being lazy easier down the road!

PIEBALDconsult 2-Dec-17 0:32am

I've been writing Extension Methods for ADO.net ... such as

@"<SqlServer Server='localhost' Database='master' />".ExecuteReader ( "SELECT ..." ... )

Dave Kreskowiak 2-Dec-17 10:58am

Interesting. Save a tons of boilerplate work.

You're passing in XML? Other options in that XML?

PIEBALDconsult 2-Dec-17 11:18am

At work I access a dozen or more databases of various flavors -- SQL Server, Oracle, Teradata, MySQL, etc.
I use XML because then I can have a config file with many such connections defined and I can refer to them by name.
The Attributes are as appropriate for the particular ADO.net Provider. Plus a Name Attribute is supported by the code that reads the config file into a Dictionary.
The parsing of the XML is handled by Provider-specific Factory classes.

Dave Kreskowiak 2-Dec-17 11:22am

Now that is slick! I like it. I might just have to steal the idea. I'm not hitting more than just a couple of SQL Server and Oracle databases at the same time, but it sounds like it's worth implementing.

PIEBALDconsult 2-Dec-17 11:42am

Thanks. I'll likely write up an article and prepare for the slings and arrows from the peanut gallery.

Dave Kreskowiak 2-Dec-17 13:48pm

I don't think you're going to get much in the way of bad comments on that one.

PIEBALDconsult 2-Dec-17 14:05pm

Have you ever read the comments on my articles? :D It's a hoot.

Dave Kreskowiak 2-Dec-17 15:02pm

:-D