[In Java] How do you check if a file is opened or not?

What I have so far:

import java.util.Scanner;

public static void main(String args[]) {

try {

while(/*args[0] is open?*/){}

Scanner file = new Scanner(System.in);

System.out.println("Please type your file name (e.g. simple.x): ");

String xFile = file.next();

args[0] = xFile;

System.out.println("File opened was: " + args[0]");

}

catch (Exception e) {

}

}