距离旅行循环帮助Java

Question

I've been racking my brain trying to figure out why my program isn't looping right. Rather than getting each hour increments I'm only getting the final hour/speed. So if I put that I'm going 40 mph for 3 hours I only get 120.

Here is the problem:

The distance a vehicle travels can be calculated as follows: Distance = Speed * Time For example, if a train travels 40 miles-per-hour for three hours, the distance traveled is 120 miles. Write a program that asks for the speed of a vehicle (in mph) and the number of hours it has traveled. It should use a loop to display the distance a vehicle has traveled for each hour of a time period specified by the user. For example, if a vehicle is traveling at 40 mph for a three-hour time period, it should display a report similar to the one that follows: Hour Distance Traveled

1 40

2 80

3 120

import java.util.Scanner;

public class Distance{
  public static void main(String [] args){
  Scanner keyboard = new Scanner(System.in);

  int time , speed ,  hour;
  double  distance;

  System.out.println("How fast were you going ?");
  speed = keyboard.nextInt();

  while(speed<=0)
  {
     System.out.println("Please enter a valid speed ");
     speed = keyboard.nextInt();
  }

  System.out.println(" How long did you ride / drive ?");
  time = keyboard.nextInt();

  while(time<=0)
  {
     System.out.println("Please enter a valid time ");
     time = keyboard.nextInt();
  }

  System.out.println(" Hour                         Distance");
  System.out.println("---------------------------------");
  hour = 0;


  for( int x = 1; x<=time; x++)
  {
     hour++;
     if(hour>1)
     {
        distance = time * speed;
        System.out.println(time+ "                " +distance);
     }
    }
   }
  }

Answer 1

use hour inside your loop instead of time,

 for( int x = 1; x<=time; x++) {
     hour++;
     if(hour>1) {
         distance = hour * speed;
         System.out.println(hour+ "                " +distance);
     }
 }

or just use x

Answer 2

Delete the variables hour and distance .

Change the name of the loop variable from x to hour .

Simply your loop to:

for( int hour = 1; hour <= time; hour++)
    System.out.println(hour+ " " + (hour * speed));

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Note that if you did used your distance variable, it was a double which is the wrong type, because:

• both speed and time are int , so distance must be int
• the output of a double has a decimal point, but your requirements did not show one