duplicate local variable and variables cannot be resolved

Question

I\'m being given three different errors in my java code, any help?

Error one: Duplicate local variable product.

int product = input.nextInt();

Answer 1

Make variables global and you can declare a variable only once:

import java.util.Random;
import java.util.Scanner; 
class TotalSales
{
    public static void main( String args[] )
    {
        Scanner input = new Scanner( System.in );

        double sales[][] = new double [ 5 ] [ 4 ];

        double productTotal = 0.0;
        double salesPersonTotal [] = new double[ 4 ];

        System.out.print( "Enter salesperson number (-1 to end): " );
        int person = input.nextInt();

        while ( person != -1 )
        {
            System.out.print( "Enter product number: ");
            int product = input.nextInt();

            while ( person != -1 )
            {
                System.out.print( "Enter product number: " );
                product = input.nextInt();
                System.out.print( "Enter sales amount: ");
                double amount = input.nextDouble();

                if ( person >= 1 && person <5 &&
                product >= 1 && product <6 && amount >=0 )
                    sales[ product - 1 ] [ person -1 ] += amount;
                else
                    System.out.println("Invalid input!" );

                System.out.print( "Enter slaesperson number (-1 to end): " );
                person = input.nextInt();
            }



            for (int column = 0; column < 4; column++ )
                salesPersonTotal[ column ] = 0;
            System.out.printf( "%8s%14s%14s%14s%14s%10s\n",
                    "Product", "Salesperson 1", "Salesperson 2",
                    "Salesperson 3", "Salesperson 4", "Total" );
            for ( int row = 0; row < 5; row++ )
            {
                System.out.printf( "%8d", (row+1));

                for ( int column = 0; column < 4; column ++ ) {
                    System.out.printf( "%14.2f", sales[row] [column]);
                    productTotal += sales[row][column];
                    salesPersonTotal[column] += sales[row][column];
                }
                System.out.printf( "%10.2f\n", productTotal );
            }

            System.out.printf( "%10.2f\n",  productTotal );
        }

        System.out.printf( "%8s", "Total" );

        for (int column = 0; column < 4; column++ )
            System.out.printf( "%14.2f",  salesPersonTotal[ column ]);

        System.out.println();
    }
}