Question

我正在读Java课程，我已经解决了这篇文章，一切正常，但有一件事。我想知道每个间隔中有多少随机数。您可以通过查看下面的代码来查看我的意思，我在其中插入[amount]我想要的随机数。我似乎没有得到正确的逻辑。任何人都可以帮助我吗？

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

    System.out.print("How many random numbers from 0 to 999? ");
    int amount = in.nextInt();


    int[] numbers = new int[amount];
    System.out.print("Here is the random numbers: ");
    for (int i = 0; i < numbers.length; i++) 
    {
        numbers[i] = (int) Math.floor(Math.random()*1000);
        System.out.print(numbers[i] + " ");
    }
    System.out.println("");


    System.out.print("These [amount] numbers are from 0 to 499: ");
    for (int i = 0; i < numbers.length; i++) 
    {
        if (numbers[i] <= 499)
        {
            int[] numbersLow = Arrays.copyOf(numbers, numbers.length);
            System.out.print(numbersLow[i] + " ");
        }       
    }
    System.out.println("");


    System.out.print("These[amount] numbers are from 500 to 999: ");
    for (int i = 0; i < numbers.length; i++) 
    {
        if (numbers[i] >= 500)
        {
            int[] numbersHigh = Arrays.copyOf(numbers, numbers.length);
            System.out.print(numbersHigh[i] + " ");
        }
    }

}

Answer 1

首先，System.out部分需要在循环之后，你怎么可能知道呢？：）

然后int [] numbersLow对我没有任何意义。如果您只想计算低于500的数字，请执行以下操作：

int counterbelow = 0;
System.out.print("These are the numbers between 0 and 499");
for (int i = 0; i < numbers.length; i++) 
{
    if (numbers[i] <= 499)
    {
        counterbelow++;
        System.out.print(numbers[i] + " ");
    }       
}

System.out.print("These are "+counterbelow+" numbers");

Answer 2

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

    System.out.print("How many random numbers from 0 to 999? ");
    int amount = in.nextInt();
    int lowerCounter=0;
    int higherCounter=0;
    List<Integer> lowerList = new ArrayList<Integer>();
    List<Integer> higherList = new ArrayList<Integer>();

    int[] numbers = new int[amount];
    System.out.print("Here is the random numbers: ");
    for (int i = 0; i < numbers.length; i++) 
    {
        numbers[i] = (int) Math.floor(Math.random()*1000);
        System.out.print(numbers[i] + " ");
        if (numbers[i] <= 499) {
            lowerCounter++;
            lowerList.add(numbers[i]);
        }
        else {
            higherCounter++;
            higherList.add(numbers[i]);
        }
    }
    System.out.println("");


    System.out.print("These ["+lowerCounter+"] numbers are from 0 to 499: ");
    for (int i:lowerList) 
    {
        System.out.print(i + " ");    
    }
    System.out.println("");


    System.out.print("These ["+higherCounter+"] numbers are from 500 to 999: ");
    for (int i:higherList) 
    {
        System.out.print(i + " ");    
    }
}

Answer 3

将输出放在循环下方;）

int amount = 0;
int[] numbersLow = new int[numbers.length];
for (int i = 0; i < numbers.length; i++) 
{
    if (numbers[i] <= 499)
    {
        numbersLow[amount] = numbers[i];
        amount++;
    }       
}
System.out.println("These " + amount + " numbers are from 0 to 499: ");
for (int n: numbersLow) 
    System.out.print(n + " ")

如何检查阵列中有多少数字在499以下？

3 个答案: