Question

我希望能够一遍又一遍地循环我的程序，具体取决于用户输入。您能否请看下面的代码并帮助我了解如何做到这一点......

import java.util.*;

public class Lab4 {
    public static void main(String[] args){
        System.out.println("Body Fat Calculator");

        double A1,A2,A3,A4,A5,B; //female
        double a1,a2,b; //male
        double bodyWeight,wristMeasurement,waistMeasurement,hipMeasurement,forearmMeasurement; //both
        double bodyFat,bodyFatpercent; //both

        Scanner body = new Scanner (System.in);

        System.out.println ("Enter Gender (m/f): ");
        char gender = body.nextLine().charAt(0);

        while ((gender != 'm') && (gender != 'f')) {
            System.out.println ("Unknown gender, Enter gender again (m/f); ");
            gender = body.nextLine ().charAt(0);
        }

        do {
            if (gender == 'm') {
                System.out.println ("Enter Your Body Weight: ");
                bodyWeight = body.nextInt ();

                System.out.println ("Enter Your Waist Measurement: ");
                waistMeasurement = body.nextDouble ();

                a1 = (bodyWeight * 1.082) + 94.42; //male formula
                a2 = waistMeasurement * 4.15;
                b = a1 - a2;

                bodyFat = bodyWeight - b;
                bodyFatpercent = bodyFat * 100 / bodyWeight;

                System.out.printf ("%s %.2f%%%n", "Your Bodyfat Percentage is: ", bodyFatpercent);
            }

            else {

                System.out.println ("Enter Your Body Weight: ");
                bodyWeight = body.nextInt ();

                System.out.println ("Enter Your Wrist Measurement: ");
                wristMeasurement = body.nextDouble ();

                System.out.println ("Enter Your Waist Measurement: ");
                waistMeasurement = body.nextDouble ();

                System.out.println ("Enter Your Hip Measurement: ");
                hipMeasurement = body.nextDouble ();

                System.out.println ("Forearm Your Measurement: ");
                forearmMeasurement = body.nextDouble ();

                A1 = (bodyWeight * 0.732) + 8.987; // female formula
                A2 = wristMeasurement / 3.14; //at fullest point
                A3 = waistMeasurement * 0.157; //at navel
                A4 = hipMeasurement * 0.249; //at fullest point
                A5 = forearmMeasurement * 0.434; //at fullest point
                B = A1 + A2 - A3 - A4 + A5;

                bodyFat = bodyWeight - B;
                bodyFatpercent = bodyFat * 100 / bodyWeight;
                System.out.printf ("%s %.2f%%%n", "Your Bodyfat Percentage is: ", bodyFatpercent);
            }
        }
        while (true){
            System.out.println ("Would You Like to Use the Calculator Again (y/n)? ");
            char answer = body.nextLine();
            // should loop here to run the program again
        }      
    }

Answer 1

通过将代码移到单独的方法中然后一遍又一遍地调用该方法，可以相对容易地完成...

public void runMyCode(){
  // Put all your code in here
  }

public static void main(String[] args){
  boolean runAgain = true; // start off being true, so it will enter the loop for the first time

  while(runAgain){
    runMyCode(); // runs your code

    // when your code has been run once, it will come back here and ask this question
    System.out.println ("Would You Like to Use the Calculator Again (y/n)? ");
    char answer = body.nextLine();

    // we change the value of the boolean so that the while loop will repeat again only if the user enters 'y'
    if (answer == 'y'){
      runAgain = true;
      }
    else {
      runAgain = false;
      }
    }
  }

main()方法只是控制程序的重复。所有其他问题和处理都在runMyCode()方法中进行。

Answer 2

将while或for循环与您要循环的整个代码一起使用。例如：

while( IsConditionTrue() ){
    System.out.println ("Enter Gender (m/f): ");
    char gender = body.nextLine().charAt(0);
    // more code
    // code to update the variable using which the condition is checked 
}

，其中

IsConditionTrue() returns a boolean value depending on the termination condition of your loop.

不要忘记更新用于在循环体中检查条件的变量。

我如何循环我的整个程序？

2 个答案: