Question

I keep getting the compilation error: pass the filename from command line arguement... Can you please tell me what im doing wrong? here is the code:

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class ShipDemo
{
public static void main(String[] args)
{
String companyName;
int num_ships, total_passengers=0, total_tonnage=0;
Ship[] shipInventory;
try
{
if(args.length == 1)
{
File file = new File(args[0]);
Scanner fileScan = new Scanner(file);
companyName = fileScan.nextLine();
num_ships = fileScan.nextInt();
shipInventory = new Ship[num_ships];
int n=0;
String type,name;
int value,year;
System.out.println("\nWelcome to ship by M. Silva");
System.out.printf("\n %-20s","Ship name Type");
System.out.println("\n-------------------------------");
while(fileScan.hasNextLine() && n<num_ships)
{
type = fileScan.next();
name = fileScan.next();
year = fileScan.nextInt();
value = fileScan.nextInt();
if(type.equals("c"))
{
shipInventory[n] = new CruiseShip(name.replaceAll("_", " "),year,value);
}else if(type.equals("C"))
{
shipInventory[n] = new CargoShip(name.replaceAll("_", " "),year,value);
}
n++;
}
for (Ship ship : shipInventory)
{
if (ship instanceof CruiseShip)
{
total_passengers += ((CruiseShip) ship).getPassengers();
System.out.println(((CruiseShip) ship));
}else
{
total_tonnage += ((CargoShip) ship).getTonnage();
System.out.println(((CargoShip) ship));
}
}
System.out.println("\nTotal Ships : "+shipInventory.length);
System.out.println("Total Passengers : "+total_passengers);
System.out.println("Total Tonnage : "+total_tonnage);
}else
System.out.println(" Pass the filename from command line argument");
} catch (FileNotFoundException e)
{
e.printStackTrace();
}
}
}

Answer 1

This program is expecting the name of the file from the command line argument

So when your running the program you should provide the name of the file from the command line so that it reads the data from the file and executes the program

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