Question

在此交互式程序中，您将找到一个菜单，其中包含用于在阵列上执行不同功能的选项。该数组取自名为“data.txt”的文件。该文件包含整数，每行一个。显然，我没有包含整个代码（它太长了）。但是，我希望有人可以帮我解决在数组中找到素数的问题现在，控制台打印了素数的数组地址（[I @ 4a13ccea]）。欢迎任何建议。我的计划的一部分如下。感谢。

public static void main(String[] args) throws FileNotFoundException {
    Scanner sc = new Scanner(System.in);
    System.out.println("Welcome to Calculation Program!\n");
    startMenus(sc);

}

private static void startMenus(Scanner sc) throws FileNotFoundException {
    while (true) {
        System.out.println("(Enter option # and press ENTER)\n");

        System.out.println("1. Display the average of the list");
        System.out.println("2. Display the number of occurences of a given element in the list");
        System.out.println("3. Display the prime numbers in a list");
        System.out.println("4. Display the information above in table form");
        System.out.println("5. Save the information onto a file in table form");
        System.out.println("6. Exit");

        int option = sc.nextInt();

        sc.nextLine();

        switch (option) {
            case 1:
                System.out.println("You've chosen to compute the average.");
                infoMenu1(sc);
                break;
            case 2:
                infoMenu2(sc, sc);
                break;
            case 3:
                infoMenu3(sc);
                break;
            case 4:
                infoMenu4(sc);
                break;
            case 5:
                infoMenu5(sc);
                break;
            case 6:
                System.exit(0);
            default:

                System.out.println("Unrecognized Option!\n");
        }

    }
}
private static void infoMenu3(Scanner sc) throws FileNotFoundException {
    File file = new File("data.txt");
    sc = new Scanner(file);

    int[] numbers = new int[100];

    int i = 0;

    while (sc.hasNextInt()) {
        numbers[i] = sc.nextInt();
        ++i;
    }

    for (int j = 0; j < i; ++j) {
        System.out.print("The numbers in the file are: " + numbers[j] + " ");
    }
}
public static boolean prime(int x) {
    boolean answer = true;

    for (int i = 2; i <= x / 2; i = i + 1) {
        if (i != x) {
            if (i % x == 0) {
                answer = false;
            }
        }
    }

    return answer;
}

public static int[] primes(int[] numbers) {
    int primesCount = 0;

    for (int i : numbers) {
        if (prime(i)) {
            primesCount = (primesCount + 1);
        }
    }

    if (primesCount == 0) {
        return null;
    }

    int[] result = new int[primesCount];
    int index = 0;

    for (int i : numbers) {
        if (prime(i)) {
            result[index] = i;
            index = index + 1;
        }
    }

    return result;
}
}

Answer 1

循环遍历数组并打印每个元素，或者如果格式符合您的需要，请使用java.util.Arrays.toString(int[])方法。

Answer 2

两个分数

如果您打印这样的数组，您将获得数组的地址，而不是内部。

System.out.println("The primes in the file are: " + primes(numbers));

将此行替换为迭代primes(numbers)

的循环

第二个是，在你的public static boolean prime(int x)函数中，你有这一行

for (int i = 2; i <= x / 2; i = i + 1)

虽然这有效，但要找到一个素数哟不需要迭代直到 x / 2 。对于性能优势 x的平方根更适合。

从文件中将int存储到数组中并找到素数JAVA

2 个答案: