public class Occurrence
{
    public static void main(String[] args)
    {
        //variables
        Scanner keyboard = new Scanner(System.in);
        int numInputs = 1, temp;
        int[] numbers = new int[31];
        int[] count = new int[31];
        boolean success = false;
        //start of program
        System.out.println("How many input values [max:30]?");
        //while no valid input
        while (!success)
        {
            try
            {
                numInputs = keyboard.nextInt(); //get a number
                numInputChecker(numInputs);     //is it valid?
                success = true;                 //ok
            }
            catch (Exception e)                 //else get a new number
            {
                keyboard.nextLine();
                System.out.println("Whole numbers 1 through 30 only, please.");
            }
        }
        //reset the loop checker
        success = false;
        //read numbers to fill that array
        System.out.println("Enter " + numInputs + " numbers.");
        for(int i = 0; i < numInputs; i++)     //from 0 to max number
        {
            while (!success)                   //while no valid number
            {
                try
                {
                    numbers[i] = keyboard.nextInt();    //fill the current cell with a number
                    numberChecker(numbers[i]);          //is it valid?
                    success = true;                     //ok
                }
                catch (Exception e)                     //else get a new number
                {
                    keyboard.nextLine();
                    System.out.println("Whole numbers 0 through 9 only, please.");
                }
            }
        }
       //take the input and count each use of element
        for (int i = 0; i< numbers.length; i++)     //for 0 to max number
        {
            temp = numbers[i];  //get the current value of the cell
            count[temp]++;      //add the use of that value to a new array's cell
        }
        for(int i = 0; i < count.length; i++)   //from 0 to 9 (expected)
        {
            if (count[i] > 0 && count[i] == 1)  //if cell not empty
            {
                System.out.println(i + " " + count[i]);  //print the current cell and how many times it was used
            }
        }
    }
    static void numInputChecker(int integer) throws Exception
    {
        if ((integer < 1) || (integer > 30))    //if 0 or negative, or if 31+
        {
            throw new Exception();              //say no
        }
    }
    static void numberChecker(int integer) throws Exception
    {
        if ((integer < 0) || (integer > 9)) //if negative or 10+
        {
            throw new Exception();          //say no
        }
    }
}
</details>
# 答案1
**得分**: 3
代码中第二个循环在填充数组时出现了逻辑错误，因为 success 变量在后续的 while 循环中没有被重置。修复方法如下：
```java
for (int i = 0; i < numInputs; i++)     //从 0 到最大数
{
    while (!success)                   //当无有效数字时
    {
        try {
            numbers[i] = keyboard.nextInt();    //将当前单元格填充为数字
            numberChecker(numbers[i]);          //是否有效？
            success = true;                     //有效
        } catch (Exception e)                     //否则获取一个新数字
        {
            keyboard.nextLine();
            System.out.println("仅限 0 到 9 的整数，请重新输入。");
        }
    }
    success = false; // [amsilf]: 这是循环重置
}

try {
   keyboard.hasNextInt(); // 在这里！
   numInputs = keyboard.nextInt(); // 获取一个数字
   numInputChecker(numInputs);     // 验证它是否有效？
   success = true;                 // 行
}
...

for (int i = 0; i < count.length; i++)   //从 0 到 31（预期）
{
    if (count[i] > 0)  //如果单元格不为空
    {
        System.out.println(i + " " + count[i]);  //打印当前单元格及其使用次数
    }
}