我被分配創建一個菜單驅動程序，其中包含一個顯示菜單屏幕/獲取用戶輸入的功能，但displaymenu()始終且僅返回 0 而不是新輸入的數字。我對編程很陌生，我用谷歌搜索了我能想到的所有東西，但我很困惑。import java.util.Scanner;public class menuDriven{ public static void main(String[] args) { int menuSelection=0; double inches, centimeters, feet, meters, miles, kilometers; Scanner keyboard = new Scanner(System.in); displayMenu(keyboard, menuSelection); switch(menuSelection) { case 1: inchesToCentimeters(keyboard); break; case 2: feetToMeters(keyboard); break; case 3: milesToKilometers(keyboard); break; } } // end main public static int displayMenu(Scanner keyboard, int menuSelection) { System.out.println("1. Convert inches to centimeters"); System.out.println("2. Convert feet to meters"); System.out.println("3. Convert miles to kilometers"); System.out.println(); System.out.println("Enter your selection"); menuSelection = keyboard.nextInt(); while (menuSelection < 1 || menuSelection > 3) { System.out.println("Please enter 1, 2, or 3."); menuSelection = keyboard.nextInt(); } return menuSelection; } public static void inchesToCentimeters(Scanner keyboard) { double inches, centimeters; System.out.print("Enter the number of inches: "); inches = keyboard.nextDouble(); centimeters = inches * 2.54; System.out.println("That is equal to " + centimeters + " centimeters."); } public static void feetToMeters(Scanner keyboard) { double feet, meters; System.out.println("Enter the number of feet: "); feet = keyboard.nextDouble(); meters = feet * 0.3048; System.out.println("That is equal to " + meters + " meters."); }程序應該接受用戶輸入 1、2 或 3，然后將該數字帶到開關并顯示代碼。
2 回答
紅顏莎娜
TA貢獻1842條經驗 獲得超13個贊
Java 按值傳遞原始參數，因此盡管您在 in 中操作menuSelection參數displayMenu，但menuSelectioninmain保持與調用之前相同displayMenu。
您可以將結果分配displayMenu給menuSelection：
menuSelection = displayMenu(keyboard, menuSelection);
您還可以刪除menuSelection作為參數的傳遞并在內部聲明它displayMenu，例如：
public static int displayMenu(Scanner keyboard) {
int menuSelection=0;
//...
}
海綿寶寶撒
TA貢獻1809條經驗 獲得超8個贊
嘗試這個：
import java.util.Scanner;
public class menuDriven{
public static void main(String[] args)
{
Scanner keyboard = new Scanner(System.in);
displayMenu(keyboard);
} // end main
private static void displayMenu(Scanner keyboard)
{
System.out.println("1. Convert inches to centimeters");
System.out.println("2. Convert feet to meters");
System.out.println("3. Convert miles to kilometers");
System.out.println();
System.out.println("Enter your selection");
int menuSelection = keyboard.nextInt();
while (menuSelection < 1 || menuSelection > 3)
{
System.out.println("Please enter 1, 2, or 3.");
menuSelection = keyboard.nextInt();
}
switch(menuSelection)
{
case 1:
inchesToCentimeters(keyboard);
break;
case 2:
feetToMeters(keyboard);
break;
case 3:
milesToKilometers(keyboard);
break;
}
/* return menuSelection; */
}
private static void inchesToCentimeters(Scanner keyboard)
{
double inches, centimeters;
System.out.print("Enter the number of inches: ");
inches = keyboard.nextDouble();
centimeters = inches * 2.54;
System.out.println("That is equal to " + centimeters + " centimeters.");
}
private static void feetToMeters(Scanner keyboard)
{
double feet, meters;
System.out.println("Enter the number of feet: ");
feet = keyboard.nextDouble();
meters = feet * 0.3048;
System.out.println("That is equal to " + meters + " meters.");
}
private static void milesToKilometers(Scanner keyboard)
{
double miles, kilometers;
System.out.println("Enter the number of miles: ");
miles = keyboard.nextDouble();
kilometers = miles * 1.609;
System.out.println("That is equal to " + kilometers + " kilometers.");
}
} // end class
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