Question

我有以下代码：

    import java.util.Scanner;

    import javax.swing.JOptionPane;


    public class weatherCalc {
        public static void main(String args[]) {
            while (true) {
                int division = 8125/1000;
                Scanner in = new Scanner;
                System.out.println("How far, in inches, is it moving on a 50-mile = 0.75 in? (Please use decimels)");
                int weatherInput = in.nextInt();
                System.out.println("How long is the time period in hours? (Please use decimels)");
                int weatherTime = in.nextInt();
                int weatherOutput = weatherInput/division*50/weatherTime;
                System.out.println("The storm is travling at "+ weatherOutput +"MPH.");
            }
        }
    }

你看，“System.out.println中的系统”（以英寸为单位，它在50英里= 0.75英寸处移动？（请使用分米）“）;”带有红色的下划线以及“Scanner in = new Scanner”的结尾;我无法弄清楚为什么，我只是想为自己开发这个。我稍后可能会对它进行一些研究。如果有人能告诉我原因，那会很有帮助。

Answer 1

Scanner in = new Scanner;

应该是：

Scanner in = new Scanner(System.in);

Answer 2

Scanner in = new Scanner(System.in);

Answer 3

你的while循环应该是这样的:(观察针对每个更改过的代码指定的注释）

Scanner in = new Scanner(System.in);//Move the Scanner declaration outside loop . Don't create it every-time within the loop.
while (true) {
  int division = 8125/1000;
  System.out.println("How far, in inches, is it moving on a 50-mile = 0.75 in? (Please use decimels)");
  int weatherInput = in.nextInt();
  System.out.println("How long is the time period in hours? (Please use decimels)");
  double weatherTime = in.nextDouble();//Take double value from input as u have specified that you want input in decimals.
  double weatherOutput = weatherInput/division*50/weatherTime;//Changed weatherOutput type to double so that you get the result in double.
  System.out.println("The storm is travling at "+ weatherOutput +"MPH.");
 }

System.out.println不使用数字

3 个答案: