Question

请，我需要帮助打印这些数组。在方法“IsPrime”中它测试输入是否为素数并将它们存储在数组“prime []”中我将其设置为数组的大数，因为我不可能知道输入将获得的确切素数和“palin”数组也是如此。在最后一个for循环中，我试图打印素数数组的结果，但我得到的输出不是素数。我得到“0000000000”谢谢！

import java.util.Scanner;
import java.util.Arrays;

public class p1c {  
    private static Scanner scan;
    public static void main(String[] args){
       scan = new Scanner(System.in);
       int z;
       for(z = 0; z<2; z++){
           System.out.println("\n Please enter the first integer number:" );
           int numx = scan.nextInt();
           System.out.println("Please enter the second integer number");
           int numy = scan.nextInt();
           if ( numx < numy){ 
               isPrime(numx,numy);
           }
           else{
               System.out.print("This is invalid, try again, x must be less than y");
               System.exit(0);
           }
      }
  }

  public static int reverse(int i){
      int reverse = 0;
      while (i!= 0){
          reverse = reverse * 10;
          reverse = reverse + i % 10;
          i = i/10;
      }
      return reverse;
  }

  public static void isPrime(int numx, int numy){
      int d = 0,c;
      int prime[] = new int[50];
      int palin[] = new int[50];
      for (int i=numx; i <= numy; i++ ){
          for (c=2; c<i; c++){
              int n = i%c;
              if (n==0){
                  break;
              }
          }
          if(i == c && i != 0 && c != 0){
              prime[i]=i;
          }
          if( reverse(i)== i){
              int palindrome = i;
              palin[palindrome]= palindrome;
          }
     }  
     for(int count = 0; count < prime.length;count ++){
          d++;
          System.out.print(prime[count]);
          if(d == 10){
              System.out.println();
              d=0;
          }
      }
   }                    
}

Answer 1

我认为您的问题与您选择阵列有关。因此，当您打印出阵列的内容时，它会打印50个元素 - 大多数为0，因为这是您初始化它的原因。

请改用List<Integer>。例如： List <Integer> prime = new ArrayList<Integer> () ;

然后在if条件下，找到素数时，请prime.add(i);

打印出列表内容时，在打印内容时使用prime.size()表示循环上限，prime.get(count)。

Answer 2

如果有人想要或曾经有过这个糟糕的项目，这是最终的工作代码！

import java.util.Scanner;
import java.util.Arrays;

public class p1c {

private static Scanner scan;

public static void main(String[] args) {

    scan = new Scanner(System.in);

    int z;
    for (z = 0; z < 2; z++) {

        System.out.println("\n Please enter the first integer number:");
        int numx = scan.nextInt();

        System.out.println("Please enter the second integer number");
        int numy = scan.nextInt();

        if (numx < numy) {
            isPrime(numx, numy);

        }

        else {
            System.out.print("This is invalid, try again, x must be less than y");
            System.exit(0);
        }
    }
}

public static int reverse(int i) {

    int reverse = 0;
    while (i != 0) {
        reverse = reverse * 10;
        reverse = reverse + i % 10;
        i = i / 10;

    }
    return reverse;
}

public static void isPrime(int numx, int numy) {
    int d = 0, c;
    int x = 0;
    int prime[] = new int[1000000];
    int palin[] = new int[500000];

    for (int i = numx; i <= numy; i++) {

        for (c = 2; c < i; c++) {
            int n = i % c;
            if (n == 0) {
                break;
            }
        }

        if (i == c && i != 0 && c != 0) {

            prime[i] = i;

        }

        if (reverse(i) == i) {
            int palindrome = i;
            palin[palindrome] = palindrome;

        }
    }
    System.out.println("Prime:");
    for (int count = 0; count < prime.length; count++) {

        if (prime[count] != 0) {
            d++;
            System.out.print("\t" + prime[count]);

        }

        if (d == 10) {

            System.out.println();
            d = 0;
        }

    }
    System.out.println("\n palindromic Prime:");
    for (int counter = 0; counter < palin.length; counter++) {

        if (palin[counter] != 0) {
            x++;
            System.out.print("\t" + palin[counter]);
        }

        if (x == 10) {

            System.out.println();
            x = 0;
        }
    }
}
}

使用if-statement中的输入在java中打印数组

2 个答案: