我有一个主菜单类，可以从用户那里选择，然后使用该选项从与菜单选项相关的switch语句中选择其他类。我的代码是：
public static void main(String[] args) {
int dieOne = 0;
int dieTwo = 0;
int choice = 0;
DiceMaker dice = new DiceMaker(); // class that creates the dice
RollDice roll = new RollDice(); // class that imitates roll
DiceMenu menu = new DiceMenu();
DiceRoller series = new DiceRoller();
System.out.println("Welcome to the Dice Roll Stats Calculator!\n");
while (choice != 4) {
menu.DiceMenu();
choice = menu.getUserChoice();
switch (choice) {
case 1:
dice.diceMaker();
dieOne = dice.DieOne();
dieTwo = dice.DieTwo();
System.out.println(dice.DieOne() + dice.DieTwo());
return;
case 2:
roll.rollDice(dieOne, dieTwo);
roll.displayRoll();
return;
case 3:
series.diceRoller();
series.displayResults();
return;
case 4:
break;
}// switch (choice)
} // while (choice != 4)
}
案例是退出＆＃39;选项，所以我把switch语句放在一个while循环中，布尔条件不等于4，这样当选择设置为4时，循环就会停止。正确的案例执行但我遇到的问题是循环，因此程序在我尝试的每个案例后停止，即使选择不是4.我尝试在案例1,2和3之后使用break语句同样，当我这样做时，它只会在无限循环中重复这个案例。我试图在我自己的切口上弄清楚这一点，我找不到任何类似我看到的东西，足以让我弄清问题是什么。我猜这可能不是将来制作菜单的最佳方式。提前谢谢。
我的其余代码如下。请注意，DiceRoller类仍在构建中，但DiceMaker和RollDice类似乎正在运行。
DiceMenu课程：
public class DiceMenu
{
public static final int CHOICE_UNKNOWN = 0;
public static final int CHOICE_MAKE_DICE = 1;
public static final int CHOICE_ROLL_ONCE = 2;
public static final int CHOICE_SERIES_ROLL = 3;
public static final int CHOICE_QUIT = 4;
private int choice = 0;
Scanner scan = new Scanner(System.in);
public int DiceMenu()
{
while ( this.choice < 1 || this.choice > 4 ) // while loop keeps choices in range
{
System.out.println(" MAIN MENU\n");
System.out.println("1. Create Your Dice");
System.out.println("2. Roll Your Dice");
System.out.println("3. Perform A Series Of Rolls And Show Stats");
System.out.println("4. Exit\n");
try // avoid invalid input
{
System.out.print("Please choose an option: ");
this.choice = scan.nextInt(); // get number of sides from user
}
catch (InputMismatchException e)
{
//if input is invalid, returns to beginning of loop
System.out.println("Invalid Input. Please try again.\n");
scan.next();
continue;
}
if ( this.choice < 1 || this.choice > 4 ) // if input is out of range
// notify user before continuing
{
System.out.println("Choice must reflect menu options. (1-4)"
+ " Please try again.\n");
this.choice = 0;
}
}//while ( this.choice < 1 || this.choice > 4 )
return 0;
}
public int getUserChoice()
{
return this.choice;
}
}
RollDice类：
public class RollDice
{
private int roll;
private int rollOne;
private int rollTwo;
private int rollTotal;
public int rollDice (int dieOne, int dieTwo)
{
this.rollOne = 1 + (int)(Math.random() * dieOne);
this.rollTwo = 1 + (int)(Math.random() * dieTwo);
this.rollTotal = this.rollOne + this.rollTwo;
return 0;
}
public void displayRoll()
{
System.out.println("You roll a " + rollOne + " and a "
+ rollTwo + " for a total of " +
rollTotal + "!"); //display separate and total
//roll amounts
if ( rollTotal == 2 ) // if/else tests for special rolls
{
System.out.println("Snake Eyes!");
}
else if ( rollTotal == 7 )
{
System.out.println("Craps!");
}
else if ( rollOne == 6 && rollTwo == 6 )
{
System.out.println("Boxcars!");
}
}
}// public class DiceRoller
DiceMaker类： 公共课DiceMaker { private int sides = 0; private int dieOne; private int dieTwo;
public int diceMaker()
{
while ( sides < 4 || sides > 20 ) // while loop keeps sides within range
{
Scanner scan = new Scanner(System.in);
try // avoid invalid input
{
System.out.print("Please enter the number of sides each die "
+ "should have (must be between 4 and 20): ");
this.sides = scan.nextInt(); // get number of sides from user
}
catch (InputMismatchException e)
{
//if input is invalid, returns to beginning of loop
System.out.println("Invalid Input. Please try again.\n");
scan.next();
continue;
}
if (sides < 4 || sides > 20) // if input is out of range
// notify user before continuing
{
System.out.println("Die must have between 4 and 20 sides."
+ " Please try again.\n");
}
}//while ( sides < 4 || sides > 20 )
this.dieOne = sides;
this.dieTwo = sides;
return 0;
}
public int DieOne()
{
return this.dieOne;
}
public int DieTwo()
{
return this.dieTwo;
}
}// public class DiceMaker
答案 0 :(得分：1)
从案例1,2和3中删除return。如果return来自main，程序将终止。你想循环，所以不要这样做。但是，正如@ajb在下面的评论中指出的那样，您并不希望案件落空。所以你需要break（s）。
case 1: dice.diceMaker();
dieOne = dice.DieOne();
dieTwo = dice.DieTwo();
System.out.println(dieOne + dieTwo);
// return;
break; // <-- applies to innermost block (switch).
case 2: roll.rollDice(dieOne, dieTwo);
roll.displayRoll();
// return;
break; // <-- applies to innermost block (switch).
case 3: series.diceRoller();
series.displayResults();
// return;
break; // <-- applies to innermost block (switch).
另外，你可以使用continue（这里，它适用于最里面的循环）。最后，请记住案例4会终止循环（因为choice是4），因此您不需要case 4。