Thread: Range Calculator

I am attempting to create a range calculator that will calculate the amount of fuel needed to reach a destination. I have done what I know so far and just need help finishing up a few sections so that it is in working order. Specifically, I am having the most trouble with calculating the number of gallons and liters and the run-time error.

 
/********************************************************
 * This class will calculate the number miles a car
 * can travel given the number of gallons of fuel,
 * and the MPG of the car can achieve. 
 *
 * @author
 * @version 
 ********************************************************/
 /*******************************************************
 *  References and Acknowledgements: 
 *  
 *
 ********************************************************/
import java.util.Scanner; // needed for keyboard input
 
public class RangeCalculator
{  // START class RangeCalculator
 
	/*****************************************************
	 * main method
	 *
	 * @param 
	 * @return
	 *****************************************************/
 
	public static void main(String args[])
	{  // START main method
		System.out.print("Welcome to the CSCI200 Range Calculator.\n");			// Welcome Message
		System.out.println();
		Scanner user_input = new Scanner(System.in);
		String destination;
		System.out.print("Type the name of your destination:");
		destination = user_input.next();
		String number_of_miles;
		System.out.print( destination + " is how many miles away?");
		number_of_miles = user_input.next();
 
 
		System.out.print(  + "is not valid.  I will use 100 for the number of miles.");
		System.out.println();
 
 
		// Declarations
 
		Scanner input = new Scanner(System.in);		                // keyboard input
		int finalDestination;								// Your final destination
		int numberOfMiles;							        // # of miles needed to travel (int)
		final int MPG = 23; 								// # of miles per gallon
		final double LITERS_CONVERSION = 3.78541178;	                // conversion factor for liters
		double fuelGallons;								// # of gallons (double)
		double fuelLiters;									// # of liters (double)
 
		// Instantation
		finalDestination = destination;
		numberOfMiles = number_of_miles;
 
 
 
		// Prompts and Input
 
 
		// Action code
 
																	// Calculate number of gallons
																	// Calculate number of liters
 
		// Output
		String distance;
		System.out.print("\n%s is %d miles away.  You will need %.2f gallons, or %.4f liters of fuel.");
 
	} // END main method
 
} // END class RangeCalculator

Any help with finishing this code is appreciated! Thank you.