java如何在循环中重复进程

Question

我正在编写代码，让用户猜测数字。他们只有两次机会获得全部 如果用户输入错误（超过1-4）， 他们可以再做一次在这种情况下，用户必须回答2和4才能获得全部

System.out.println("you have only two chance to get all");
    int guessnum[] = new int[2];;        
    for (int i = 0; i < guessnum.length; i++) {
        System.out.print((i+1)+" Enter number 1-4 : ");
        int num = sc.nextInt();
        if (num == 1) {            
           System.out.println("not here");
        }
        else if (num == 2) {            
           System.out.println("wow!! you got it");
        }
        else if (num == 3) {            
           System.out.println("not here");

        }
        else if (num == 4) {            
           System.out.println("wow!! you got it");
        }   
        else {            
           System.out.println("number must be 1-4 only, try again");
          //how to repeat in same loop
        }
    }

Answer 1

使用break语句

else if (num == 2) {            
   System.out.println("wow!! you got it");
   break;
}

Answer 2

这是我所有的代码，在两个机会，用户需要把2和4赢

import java.util.Scanner;
public class test {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println("you have only two chance to get all");
        int guessnum[] = new int[2];
        int x=0;        
        for (int i = 0; i < guessnum.length; i++) {
            System.out.print((i+1)+" Enter number 1-4 : ");
            int num = sc.nextInt();
            if (num == 1) {            
               System.out.println("not here");
            }
            else if (num == 2) {            
               System.out.println("wow!! you got it");
               x++;
            }
            else if (num == 3) {            
               System.out.println("not here");

            }
            else if (num == 4) {            
               System.out.println("wow!! you got it");
               x++;
            }   
            else {            
               System.out.println("number must be 1-4 only, try again");
                --i;
            }
        }
        if (x == 0)             
               System.out.println("\nyou don't get anything");          
        if (x == 1)             
               System.out.println("\nyou got 1 only");
        if (x == 2)           
               System.out.println("\ncongrat!!!! you got all");
    }
}

Answer 3

for (int i = 0; i < guessnum.length; i++) {
            int count = 1;

            System.out.print((i+1)+" Enter number 1-4 : ");
            int num = sc.nextInt();
            if (num == 1) {
                System.out.println("not here");
            }
            else if (num == 2) {
                System.out.println("wow!! you got it");
            }
            else if (num == 3) {
                System.out.println("not here");

            }
            else if (num == 4) {
                System.out.println("wow!! you got it");
            } else {
                if (i != 2) {
                    System.out.println("number must be 1-4 only, try again,and change another number");
                } else {
                    break;
                }
                //do again in same loop
            }

           i++;
    }

你可以试试这个

Answer 4

        int i = 1;
        Scanner sc = new Scanner(System.in);
        do {
                System.out.println("you have only two chance to get all");
                System.out.print((i) + " Enter number 1-4 : ");
                int num = sc.nextInt();
                switch (num) {
                    case 1:
                        System.out.println("not here");
                        break;
                    case 2:
                        System.out.println("wow!! you got it");
                        goItOrNot = false;
                        break;
                    case 3:
                        System.out.println("not here");
                        break;
                    case 4:
                        System.out.println("wow!! you got it");
                        break;
                    default:
                        System.out.println("number must be 1-4 only, try again");
                        break;
                }
                i++;
            }
        } while (i < 3);

Answer 5

如果要使用for循环，可以在System.out.println("number must be 1-3 only, try again");之后的最后一个else块中编写类似的--i;代码

因此，此代码将解决您的问题：

System.out.println("you have only two chance to get all");
int guessnum[] = new int[2];;        
for (int i = 0; i < guessnum.length; i++) {
    System.out.print((i+1)+" Enter number 1-4 : ");
    int num = sc.nextInt();
    if (num == 1) {            
       System.out.println("not here");
    }
    else if (num == 2) {            
       System.out.println("wow!! you got it");
    }
    else if (num == 3) {            
       System.out.println("not here");

    }
    else if (num == 4) {            
       System.out.println("wow!! you got it");
    }   
    else {            
       System.out.println("number must be 1-4 only, try again");
      --i;
    }
}

更新

在我上面的回答中，我刚刚说过，如何在对原始代码进行最小更改的情况下重复for循环。正如标题中所问的那样。但是@JayPrakash说这不是一个完美的答案，所以投票否决了它。好的，让我们试着找到一个完美的：

public static void main(String[] args) {
    guess(2, 1, 4, new int[]{2, 4});
}

/**
 *
 * @param tries tries count
 * @param from from range, inclusive
 * @param to to range inclusive
 * @param puzzled array with puzzled values
 * @return array, which contains only puzzled answers from a user
 */
public static int[] guess(int tries, int from, int to, int[] puzzled) {
    if (puzzled == null || puzzled.length < 1) throw new IllegalArgumentException("puzzled");
    if (Math.abs(from - to) < 1) throw new IllegalArgumentException("range");
    if (tries < 1 || Math.abs(from - to) < tries - 1) throw new IllegalArgumentException("tries"); //`tries - 1` because `to` is inclusive
    if (from > to) {
        int tmp = from; from = to; to = tmp;
    }
    Scanner sc = new Scanner(System.in);
    int answers[] = new int[tries], //all previous user answers
        result[] = new int[tries];

    System.out.printf("You have only %d chances to get all\n", tries);
    int i = 0, j = 0;
    while (i < tries && j < puzzled.length) { // `j < puzzled.length` break if all puzzled answers is found
        System.out.printf("%d Enter number %d-%d: ", (i + 1), from, to);
        int number = sc.nextInt();
        if (number < from || number > to) {
            System.out.printf("Number must be in %d-%d range only, try again\n", from, to);
            continue;
        }
        if (contains(answers, number, i)) {
            System.out.printf("Number %d is used before\n", number);
            continue;
        }

        answers[i++] = number;
        if (contains(puzzled, number)) {
            System.out.println("Wow!! you got it");
            result[j++] = number;
        } else {
            System.out.println("Not here");
        }
    }
    if (j == puzzled.length)
        System.out.println("You got all");
    else
        System.out.printf("You got %d only\n", j);
    return Arrays.copyOfRange(result, 0, j);
}

private static boolean contains(int[] array, int value) {
    return contains(array, value, array.length);
}

private static boolean contains(int[] array, int value, int lookTo) {
    for (int i = 0; i < lookTo; i++)
        if (array[i] == value)
            return true;
    return false;
}