代码中的循环输出不正确

Question

我一直在努力使用我为作业创建的这种方法，它让我发疯。我的 if/else 语句有问题，但我似乎无法找出它是什么。这是我收到的输出：

1: Lather and Rise.
2: Lather and rinse.
Done
2: Lather and Rise.
2: Lather and rinse.
Done
3: Lather and Rise.
2: Lather and rinse.
Done

我希望看到这个：

1: Lather and rinse.
2: Lather and rinse.
Done.

我做错了什么来阻止它正确输出？任何建议/帮助表示赞赏！请参阅下面的代码：

public class ShampooMethod {

    public static void printShampooInstructions(int numCycles) {

        for (int i = 1; i < 4; i++) {
            System.out.println(i + ": Lather and Rise.");
            if (numCycles < 1) {
                System.out.println("Too few.");
            } else if (numCycles >= 4) {
                System.out.println("Too many");
            } else {
                System.out.println(numCycles + ": Lather and rinse.");
            }
            System.out.println("Done");
        }
    }


    public static void main(String[] args) {
        printShampooInstructions(2);

        return;
    }
}

Answer 1

6.4.2：带循环的方法：洗发水。

编写一个方法 printShampooInstructions()，带有 int 参数 numCycles，返回类型为 void。如果 numCycles 小于 1，则打印“太少。”。如果超过 4 个，打印“Too many.”。否则，打印“N：起泡并冲洗”。 numCycles 次，其中 N 是循环数，后跟“Done.”。以换行符结束。输入 2 的示例输出：

1：起泡并冲洗。

2：起泡并冲洗。

完成。

import java.util.Scanner;

public class ShampooMethod {

   /* Your solution goes here  */
   public static void printShampooInstructions(int numCycles) {
      if (numCycles < 1){
      System.out.println("Too few.");   
      }
      else if (numCycles > 4){
      System.out.println("Too many.");
      } 
      else {
         for(int i = 1; i <= numCycles; i++){
            System.out.println(i + ": Lather and rinse.");
         }
         System.out.println("Done.");
      }
   }

   public static void main (String [] args) {
      Scanner scnr = new Scanner(System.in);
      int userCycles;

      userCycles = scnr.nextInt();
      printShampooInstructions(userCycles);
   }
}

Answer 2

循环中的所有内容都会按照循环运行的次数执行。在这种情况下，循环执行 3 次，因为这是您设置的 (int i = 1; i

Answer 3

每次循环运行时都会输出“Lather and Rise”行，因为它不在 if/else 块内。与“完成”相同。将此行放在 for 循环之外。需要指出的另一件事，不是硬编码 4，而是将 i

public static void printShampooInstructions(int numCycles) {

    for (int i = 0; i < numCycles; i++) {
        // System.out.println(i + ": Lather and Rise.");
        if (numCycles < 1) {
            System.out.println("Too few.");
        } else if (numCycles >= 4) {
            System.out.println("Too many");
        } else {
            System.out.println(numCycles + ": Lather and rinse.");
        }   
    }
    System.out.println("Done");
}

Answer 4

查看下面的 cmets，看看是什么导致了与您预期不同的输出。

1. 您一次迭代太多了
2. System.out.println(i + ": Lather and Rise."); 将显示在循环的每一轮中，因为您没有使用if 或else 或else if 过滤它
3. 在循环之后切换System.out.println("Done"); 的位置 - 因为如果循环完成并且您处于方法的末尾，那么您就完成了。

---

public class ShampooMethod {

    public static void printShampooInstructions(int numCycles) {

        // i = 1 - i < (2+1=3) -> i will become 1 and than 2 -> done
        for (int i = 1; i < (numCycles+1); i++) {
            // this would be displayed every time you go throw the loop
            // System.out.println(i + ": Lather and Rise.");
            if (numCycles < 1) {
                System.out.println("Too few.");
            } else if (numCycles >= 4) {
                System.out.println("Too many");
            } else {
                System.out.println(i + ": Lather and rinse.");
            }
        }
        // Done goes here because only after the loop we are done
        System.out.println("Done");
    }


    public static void main(String[] args) {
        printShampooInstructions(2);

        return;
    }
}

Answer 5

    if (numCycles < 1) {
       System.out.println("Too few.");
      }
    else if (numCycles > 4) {
       System.out.println("Too many.");
      }
    else {
       for (i = 1; i <= numCycles; ++i) {
          System.out.println(i + ": Lather and rinse.");
         }
        System.out.println("Done.");
      }

我使用了一个 if else 语句，并且在 else 实例的语句末尾，我创建了一个 for 循环 来打印Lather and Rinse 语句，然后是 done，它起作用了。

Answer 6

    import java.util.Scanner;
    public class Methods_ShampooMethod_ChallengeActivity {

        public static void printShampooInstructions(int numCycles) {
            

            if (numCycles < 1) {
                System.out.println("Too few.");
            }
            else if (numCycles > 4) {
                System.out.println("Too many.");
            }
            else {
                for (int i = 1; i <= numCycles; i++) {
                    System.out.println(i + ": Lather and rinse.");         
                }
            System.out.println("Done.");           
            }                
        }

        public static void main (String [] args) {
            Scanner scnr = new Scanner(System.in);
            int userCycles;
        
            System.out.print("Enter cycles: ");
            userCycles = scnr.nextInt();
        
            printShampooInstructions(userCycles);   
        }
    }

Answer 7

公共类 ShampooMethod {

public static void printShampooInstructions(int numCycles) {
    if (numCycles < 1) {
        System.out.println("Too few.");
    } else if (numCycles > 4) {
        System.out.println("Too many.");
    } else {
        for (int i = 1; i <= numCycles; i++) {
            System.out.println(i + ": Lather and rinse.");
        }
        System.out.println("Done.");
    }
}

public static void main(String[] args) {
    Scanner scnr = new Scanner(System.in);
    int userCycles;

    userCycles = scnr.nextInt();
    printShampooInstructions(userCycles);
}

}

Answer 8

在第一个 for 循环中输入： for (int i = 1; i < numCycles; i++) 而不是这个： for (int i = 1; i < 4; i++)