Thread: My program compiles and runs, but doesn't display anything!

Hey all, first time poster here, so I'll try to abide by the rules =)

Anyway, I have a homework problem and I've got it running, but not really running. My brain is pretty fried so I'm guessing it's something silly, but if you guys could give me a hand here or point me in the right direction, it'd be very helpful. The question is asking us to rewrite an earlier example so that the size of the array is defined in the first command line argument. If there is no command argument is given, then just use 10 as the default size.

The original code is this:

public class InitArray
{
   public static void main( String args[] )
   {
      int array[]; // declare array named array
 
      array = new int[ 10 ]; // create the space for array
 
      System.out.printf( "%s%8s\n", "Index", "Value" ); // column headings
 
      // output each array element's value
      for ( int counter = 0; counter < array.length; counter++ )
         System.out.printf( "%5d%8d\n", counter, array[ counter ] );
   } // end main
} // end class InitArray

which gives me an output of:

Index Value
0 0
1 0
2 0
3 0
4 0
5 0
6 0
7 0
8 0
9 0

So now my code is as follows:

import java.util.Scanner; 
 
public class InitArray
{
   public static void main( String args[] )
   {
 
	  Scanner input = new Scanner( System.in);
 
	  int array[]; 
 
	  System.out.print("Please enter a number for the array size: ");
	  array = new int[ input.nextInt() ];
 
	  int num = input.nextInt();
	  int inputNumber = 0;
 
	  if(args.length == 0)
	  {
	      array = new int[10];
	  }
 
	  else 
	  {
		  array = new int[Integer.parseInt(args[0] ) ]; 
	  }
 
	  System.out.printf( "%s%8s\n", "Index", "Value" ); 
 
	  for ( int counter = 0; counter < array.length; counter++ )
		 System.out.printf( "%5d%8d\n", counter, array[ counter ] );
 
	}
}

which gives me an output of:

Please enter a number for the array size: 5

And it just hangs there. What am I missing? I hope I posted this is in the right subsection, since it is an array issue. Any help or guidance would be appreciated. Thanks!

hi,

Your program asking 2 inputs but you given only one input that is the problem.

Please remove the below line of code, then try to run it will run.

int num = input.nextInt(); //unnecessary line, you are not using anywhere

Why you are getting another input ?? What is the use of above line.??



Thanks,

Welcome to the forum! Thanks for taking the time to learn to post code correctly.

Originally Posted by Ganeprog

hi,

Your program asking 2 inputs but you given only one input that is the problem.

Please remove the below line of code, then try to run it will run.

int num = input.nextInt(); //unnecessary line, you are not using anywhere

Why you are getting another input ?? What is the use of above line.??



Thanks,

I guess I've done so many revisions to the code, that line probably just lingered in there and I didn't notice. But even with that line removed, the output still looks like:

Please enter a number for the array size: 5
Index   Value
    0       0
    1       0
    2       0
    3       0
    4       0
    5       0
    6       0
    7       0
    8       0
    9       0

regardless of what number I put in. Does it have anything to do with these lines?

if(args.length == 0)
array = new int[Integer.parseInt(args[0] ) ];

I tried messing around with them some but it kept throwing some errors.

Thanks for the warm welcome BTW!

You define an array in 3 different places, the first being completely pointless, because it will be redefined later. Your logic is confused, non-compliant with the assignment's instructions, and out of order.

The assignment says: "(create an array of) the size defined in the first command line argument. If no command (line) argument is given, then just use 10 as the default size."

Code that. In pseudo code, it looks something like:

if args.length == 0
array = new int[10]
else
array = new int[ args[0] ]

You don't need a Scanner object. Where in the assignment does it say to ask the user for input? Or is that a holdover from the previous assignment? Sometimes it's better to start over.

Don't let friends code with fried brains. Get some rest.