Class File and it's constructors

[jisoo22]

Hello all,

I have a small program that has a method which uses the File class and it's exists() method. Unfortunately I think I'm constructing it wrong or something because I get a compile-time error saying that my constructor is an invalid statement. Can someone tell me the correct way to do it? My snippet of code is below so you can kind of see what I'm attempting to do. It takes in a file name (i.e. "temp.txt&quot and checks to see if it exists or not.

Thanks,
Jisoo22

import java.io.*;

public class simModel_2_1 {

	public static void main (String args[])

	{
          String fileName = "world.txt";
          fileName = checkReadFile(fileName, args);
          System.out.println(fileName);//debugging

	}

	public static String checkReadFile(String file, String [] args)

	{
		String temp;
		String str;

		if (str.length() > 0)
		{
			temp = str;
		}
		else
		{
			temp = file;
		}


		while (temp.equalsIgnoreCase("q") == false)

			File f = new File(temp);

			if(f.exists() == true)
			{

				return temp;

			}
			else
			{
				System.out.println("The simulation data file " + temp +
								   "cannot be read.");
				System.out.println("Enter a new file name or 'Q' to quit: ");
				str = Keyboard.readString();
			}
	}//checkReadFile
}//class simModel_2_1
[code]

 

[jbourne68]

I hope this will answer you question. It looks like you are doing a couple things wrong. First, when you want to call a static method on a class you must call ClassName.theMethod() or create an instance of the class and then call a method. If you want to open a file to read the best thing to do is to create a FileInputStream and pass it the path of the file you wish to open. If all you care about is whether the file exist try opening and when the JVM throws a FileNotFoundException you will know the file is not there. It is a checked exception and java will force you to handle it. Hope this helps.