Java - array size not updating

Read whole numbers from a user, then display the list of numbers input and the frequency of each value. The number of inputs should vary from 1-30, and the values accept 0-9.

My issue is that the array always defaults to 1 even if I change it to int[] numbers = new int[numInputs];. It appears that numInputs gets written over to 1 during the first for loop but even changing the value of numInputs it still caps out at 1. I'm sure my logic is wrong but I'm not sure where.

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
}

注意：上述内容为你要翻译的代码部分，不包含其他额外的内容。

        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.");
            }
        }
        success = false; // [amsilf]: That's the cycle reset
    }

答案2

得分: 1

可能会出现java.util.NoSuchElementException并捕获错误以处理此块。

在使用keyboard.nextInt()之前使用keyboard.hasNextInt()。

像这样！

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
}
...

try {
   keyboard.hasNext(); // here!
   numInputs = keyboard.nextInt(); //get a number
   numInputChecker(numInputs);     //is it valid?
   success = true;                 //ok
}
...

答案3

得分: 0

在最后的 for 循环中应该是这样的：

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
    }
}

    for(int i = 0; i < count.length; i++)   //from 0 to 31(expected)
    {

        if (count[i] > 0)  //if cell not empty
        {
            System.out.println(i + " " + count[i]);  //print the current cell and how many times it was used
        }
    }