store string in array using scanner

Question

I have a file in path d:\input.txt I want get this path from user with Scanner class Here is my code but i recevie ArrayIndexOutOfBoundException Why?

if(args.length != 0)
        {
            readerWriter.readFile(args[0]);
        }
        else
        {
            System.out.println("Plese enter the path of your file");                
            Scanner filePath = new Scanner(System.in);
            args[0] = filePath.next();
            readerWriter.readFile(args[0]);
        }

Answer 1

You can't using array here args[0] = filePath.next(); because your array is not initialized and give ArrayIndexOutOfBoundException, try:

String file = filePath.next(); readerWriter.readFile(file);

Answer 2

It is simple, if

args.length == 0

you cannot access

args[0]

So you have to change the lines,

args[0] = filePath.next();
readerWriter.readFile(args[0]);

into

String myPath = filePath.next();
readerWriter.readFile(myPath);

Answer 3

This will happen if args.length is 0.

You should do

if(args.length != 0)
        {
            readerWriter.readFile(args[0]);
        }
        else
        {
            System.out.println("Plese enter the path of your file");                
            Scanner filePath = new Scanner(System.in);
            readerWriter.readFile(filePath.next());
        }

and not use args[0] in else.

Program will go in else block if args.length == 0 and args[0] = filePath.next(); will give ArrayIndexOutOfBoundException