结束do-while循环 [英] ending a do-while loop
本文介绍了结束do-while循环的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
好吧，我有一个do-while循环，该循环应该在使用次数达到 q时结束，但它给了我错误消息，请帮忙。
Ok I have a do-while loop that's supposed to end when the use hits 'q' but it is giving me the error message instead please help.
package Assignments;
import java.util.*;
public class assignment3 {
public static void main(String[] args) {
//Scanner
Scanner stdIn = new Scanner(System.in);
//Variables
final double METERS_TO_CM = 100; // The constant to convert meters to centimeters
final double BSA_CONSTANT = 3600; // The constant to divide by for bsa
double bmi; // Body Mass Index
double weight; // Weight in kilograms
double height; // Height in meters
String classification; // Classifies the user into BMI categories
double bsa; // Body surface area
System.out.print("Welcome to the BMI and BSA Calculator to begin enter weight in kilograms.");
weight = stdIn.nextDouble();
System.out.print("Enter height in meters: ");
height = stdIn.nextDouble();
bmi = weight/(height*height); // Calculates BMI
bsa = Math.sqrt(((height*METERS_TO_CM)*weight)/BSA_CONSTANT); // Calculates BSA
if (bmi < 18.5)
{
classification = "Underweight";
}
else if (bmi < 25)
{
classification = "Normal";
}
else if (bmi < 30)
{
classification = "Overweight";
}
else
{
classification = "Obese";
}
System.out.println("Choose Options below to set height and weight");
System.out.println("Your classification is: " + classification);
System.out.println("(H)eight: " + height + " meters");
System.out.println("(W)eight: " + weight + " kilograms");
System.out.printf("BMI: %.1f\n", bmi);
System.out.printf("BSA: %.2f\n", bsa);
System.out.println("(Q)uit");
String response = stdIn.next();
do {
if (response.charAt(0)== 'w')
{
System.out.println("Enter new weight: ");
weight = stdIn.nextDouble();
System.out.println("Choose Options below to set height and weight");
System.out.println("Your classification is: " + classification);
System.out.println("(H)eight: " + height + " meters");
System.out.println("(W)eight: " + weight + " kilograms");
System.out.printf("BMI: %.1f\n", bmi);
System.out.printf("BSA: %.2f\n", bsa);
System.out.println("(Q)uit");
bmi = weight/(height*height);
bsa = Math.sqrt(((height*METERS_TO_CM)*weight)/BSA_CONSTANT);
response = stdIn.next();
}
else if (response.charAt(0) == 'h')
{
System.out.println("Enter new height: ");
height = stdIn.nextDouble();
System.out.println("Choose Options below to set height and weight");
System.out.println("Your classification is: " + classification);
System.out.println("(H)eight: " + height + " meters");
System.out.println("(W)eight: " + weight + " kilograms");
System.out.printf("BMI: %.1f\n", bmi);
System.out.printf("BSA: %.2f\n", bsa);
System.out.println("(Q)uit");
bmi = weight/(height*height);
bsa = Math.sqrt(((height*METERS_TO_CM)*weight)/BSA_CONSTANT);
response = stdIn.next();
}
else if (response.charAt(0)!= 'w')
{
System.out.println("That is not a valid choice try again");
response = stdIn.next();
}
else if (response.charAt(0)!= 'h')
{
System.out.println("that is not a valid choise try again");
response = stdIn.next();
}
else if (response.charAt(0) == 'q')
{
break;
}
} while (response != "q");
}
}
推荐答案
q 不等于 w 或 h 。因此，如果（response.charAt（0）！='w'），则 else的条件成立，因此您不会实际使用 else如果（response.charAt（0）=='q'）条件中断。
q is not equal to either w or h. So, condition is true for else if (response.charAt(0)!= 'w') and so you aren't going to actual else if (response.charAt(0) == 'q') condition to break.
因此，将最后3个 else if 以这种方式-
So, place your last 3 else if in this fashion -
else if (response.charAt(0) == 'q')
{
break;
}
else if (response.charAt(0)!= 'w')
{
System.out.println("That is not a valid choice try again");
response = stdIn.next();
}
else if (response.charAt(0)!= 'h')
{
System.out.println("that is not a valid choise try again");
response = stdIn.next();
}
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