我试图计算素数，但在素数内部有问题

Question

//i have this so far

public class Primes {
    private boolean[] nums;
    private int upperbound;

    public Primes(int n) {

        nums = new boolean[n + 1];
        for (int i = 2; i <= n; i++)
            nums[i] = true;
    }

    public static final int DEFAULT_UPPER_BOUND = 100 + 1;

    public boolean isPrime(int x) {
        if (nums[x] == true) {
            return true;
        } else {
            return false;
        }
    }

    public boolean isComposite(int x) {
        if (nums[x] == true) {
            return false;
        } else {
            return true;
        }
    }

    public int getPrimesWithin(int min, int max) {
        for (int n = min; n <= max; n++) {
            if (nums[n] == true) {
                return n;
            }

        }
        return max;

    }

    public String toString() {
        String a = "";
        a += (nums) + " ";
        return a;
    }

    public int getUpperBound() {
        return nums.length;
    }

    public int nthPrime(int n) {
        int count = 0;
        int index = 2;

        while (count < n) {
            if (nums[index] = true) {
                count++;
            }
        }
        return index;
    }

    public void computePrimes(int x) {
        for (int i = 2; i * i <= x; i++) {
            if (nums[i]) {
                for (int j = i; i * j <= x; j++) {
                    nums[i * j] = false;
                }
            }
        }
    }

    void changeUpperBound(int x) {
        upperbound = x;
    }

}

//it needs to fit this

public class Prime {
    public static void main(String[] args) {
        Primes somePrimes = new Primes();
        System.out.println("Default Prime object");
        System.out.println(somePrimes);
        System.out.println("Upper Bound: " + somePrimes.getUpperBound());
        System.out.println("4th prime: " + somePrimes.nthPrime(4));
        System.out.println("7 prime?: " + somePrimes.isPrime(7));
        System.out.println("7 composite?: " + somePrimes.isComposite(7));
        somePrimes.changeUpperBound(50);
        System.out.println(somePrimes);
        int[] primes = somePrimes.getPrimesWithin(40, 50);
        System.out.print("Primes between 40 and 50: ");
        for (int p : primes)
            System.out.print(p + " ");
        System.out.println();

        System.out.println("*******************");

        Primes myPrimes = new Primes(53);
        System.out.println(myPrimes);
        System.out.println("Upper Bound: " + myPrimes.getUpperBound());
        System.out.println("10th prime: " + myPrimes.nthPrime(10));
        System.out.println("15 prime?: " + myPrimes.isPrime(15));
        System.out.println("15 composite?: " + myPrimes.isComposite(15));
        myPrimes.changeUpperBound(200);
        System.out.println(myPrimes);
        int[] primes2 = myPrimes.getPrimesWithin(50, 97);
        System.out.print("Primes between 50 and 97: ");
        for (int p : primes2)
            System.out.print(p + " ");
        System.out.println();
    }
}

// i am not sure how to make the primeswithin work and if you notice any other errors there are probably several

素数类规范：

实例字段:
私有布尔[]数；//您可以选择另一个逻辑名称//是一个所需大小的变量，或者我们可以只使用.length？

素数通过53：2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53上界：53第10素数：29 15素数？：假15复合？：真素数通过200：2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 71 73 79 83 89 97 101 103 107 109 113 127 131 137 139 149 149 151 157 167 163 173 173 181 193 197 193 197 199 191 193 197 199 199素数在50和97之间：53 59 61 67 73 79 83 89 97

Answer 1

使用ArrayList 而不是int[]作为PrimesInde的返回类型。在所需范围内遍历大数组，对于每个素数，将其添加到ArrayList。