Java while循环它没有问循环后的第一个提示

Question

谢谢你的建议，这是我第一次在stackoverflow上，因为我是编程的新手。我遇到的问题是我的程序在执行while循环后没有要求输入名称。

import java.util.*; 
import java.lang.*; 

/** 
* CS-12J 
* Sweetner.java 
* Purpose: 
* 
* @version 1.0 3/18/13 
*/ 

public class Sweetner { 

    /** 
    * The main method begins the execution of the program 
    * 
    *@param args not used 
    */ 

    public static void main (String[] args) { 
     Scanner input = new Scanner(System.in); 
     String again = "yes"; 
     while(again.equals("yes")) { 
      System.out.print("Enter the dieter's name: "); 
      String name = input.nextLine(); 
      System.out.print("/n Enter the target weight of the dieter in pounds: "); 
      double weightInPounds = input.nextDouble(); 

      //converts pounds to grams 
      final double IBS_TO_GRAMS = 453.59; 
      double weightInGrams = weightInPounds * IBS_TO_GRAMS; 

      //finds lethal amout of sweetner for mouse 
      double mouseWeight = 30; 
      double lethalDoseMouse = 100; 
      final double MOUSE_LETHAL_PROPORTION = 
       (double) lethalDoseMouse/mouseWeight; 

      //finds lethal amount of sweetner for human of given weight 
      double lethalSweetner = MOUSE_LETHAL_PROPORTION * weightInGrams; 

      //lethal number of cans 
      final double SODA_SWEETNER = 0.001; 
      final double SODA_GRAMS = 350; 
      double lethalCans = lethalSweetner/(SODA_SWEETNER * SODA_GRAMS); 

      //output 
      System.out.println("For dieter: " + name); 
      System.out.println("Dieter's target weight: " + weightInPounds 
       + " pounds"); 
      System.out.println("Lethal dose in grams of sweetner is: " 
       + lethalSweetner); 
      System.out.println("Lethal number of cans of soda: " 
       + lethalCans); 

      //extra credit 
      final int CANS_PER_DAY = 15; 
      final double DAYS_IN_YEAR = 365.25; 
      double yearsToLethal = lethalCans/(CANS_PER_DAY * DAYS_IN_YEAR); 
      System.out.println("Years to lethal dose: " + yearsToLethal); 
      System.out.println("Do you want to repeat the program? yes or no"); 
      again = input.next(); 
     } 
    } 
} 

Answer 1

试试这个：

import java.util.*; 
import java.lang.*; 

/** 
* CS-12J 
* Sweetner.java 
* Purpose: 
* 
* @version 1.0 3/18/13 
*/ 

public class Sweetener { 

    /** 
    * The main method begins the execution of the program 
    * 
    *@param args not used 
    */ 

    public static void main (String[] args) { 
     Scanner input = new Scanner(System.in); 
     String again = "yes"; 
     while(again.equals("yes")) { 
      System.out.print("Enter the dieter's name: "); 
      String name = input.nextLine(); 
      System.out.print("Enter the target weight of the dieter in pounds: "); 
      double weightInPounds = Double.valueOf(input.nextLine()); 

      //converts pounds to grams 
      final double IBS_TO_GRAMS = 453.59; 
      double weightInGrams = weightInPounds * IBS_TO_GRAMS; 

      //finds lethal amout of sweetner for mouse 
      double mouseWeight = 30; 
      double lethalDoseMouse = 100; 
      final double MOUSE_LETHAL_PROPORTION = 
        (double) lethalDoseMouse/mouseWeight; 

      //finds lethal amount of sweetner for human of given weight 
      double lethalSweetner = MOUSE_LETHAL_PROPORTION * weightInGrams; 

      //lethal number of cans 
      final double SODA_SWEETNER = 0.001; 
      final double SODA_GRAMS = 350; 
      double lethalCans = lethalSweetner/(SODA_SWEETNER * SODA_GRAMS); 

      //output 
      System.out.println("For dieter: " + name); 
      System.out.println("Dieter's target weight: " + weightInPounds 
        + " pounds"); 
      System.out.println("Lethal dose in grams of sweetner is: " 
        + lethalSweetner); 
      System.out.println("Lethal number of cans of soda: " 
        + lethalCans); 

      //extra credit 
      final int CANS_PER_DAY = 15; 
      final double DAYS_IN_YEAR = 365.25; 
      double yearsToLethal = lethalCans/(CANS_PER_DAY * DAYS_IN_YEAR); 
      System.out.println("Years to lethal dose: " + yearsToLethal); 
      System.out.print("Do you want to repeat the program? yes or no"); 
      again = input.nextLine(); 
     } 
    } 
}