我如何循环我的整个程序？

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。 你能不能看下面我的代码并帮助我理解如何做到这一点……

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它…

 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发生在runMyCode()方法中。

Answer 2

for您要循环的整个代码使用while或for循环。 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 } 

哪里

 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。