How to print a text notification beside prime fibonacci numbers?

问题

This is an assignment from a grade 12 computer science class.

The section of the assignment I am having difficulty with reads as follows:

Determine which of the first 20 Fibonacci numbers are prime numbers.
Put a “this is a prime” text notification in the printout from the Basic challenge.
Store the FibPrimes in an array called FibPrimes.

Here is what I have attempted:

Near the bottom, I attempted to make a loop that would print the text notification "This is a prime" if the given FibNum element was equal to a FibPrime element. This did not work. The problem block is identified with a comment. The rest of the program is okay.

package fibonaccinumbers;

public class FibonacciNumbers {

    public static void main(String[] args) {

        // Creation of Fibonacci Numbers Array.
       int [] FibNums = new int[20];
        FibNums[0] = 0;
        FibNums[1] = 1;

        // Creation if Fibonacci Primes Array.
        int [] FibPrimes = new int[7];
        FibPrimes[0] =  2;
        FibPrimes[1] =  3;
        FibPrimes[2] =  5;
        FibPrimes[3] =  13;
        FibPrimes[4] =  89;
        FibPrimes[5] =  233;
        FibPrimes[6] =  1597;

        // Printing first two fibonacci numbers.
        System.out.println(0);
        System.out.println(1 + "*");

        // Printing remaining fibonacci numbers up to 20th term.
        for (int i=2; i<FibNums.length;i++){ // Begin number generation loop.
            FibNums[i] = FibNums[i-1] + FibNums[i-2];

            // Checks if the fibonacci number is odd.
            // A number is not odd if two divides into it evenly.
            boolean oddcheck = true;
            if (FibNums[i]%2==0){
                oddcheck = false;
            }

            // Prints odd fibonacci numbers with a star beside it.
            // Prints even fibonacci numbers with no star beside it.
            if (oddcheck == true){
            System.out.println(FibNums[i] + "*");
            } else {
            System.out.println(FibNums[i]);    
            }

            // PROBLEM BLOCK HERE. ************************
            // If any element in the FibPrimes array is equal to the FibNums 
            // array, then the number is a prime.
            for (int n=0; n<=FibPrimes.length; n++){
                if (FibNums[i] == FibPrimes[n]){
                    System.out.print(" " + "This is a prime.");
                }
            }


        } // End number generation loop.

    }

}

Output with problem block removed:

(The stars identify odd numbers - from a different section of the assignment)

Output with problem block remaining:

0
1*
1*

Notice that the rest of the numbers do not print and there is no text notification.

There are likely better ways to solve the problem than I currently have, but I will continue to revise this. Let me know if you need any more information. Thank you.

Thank you @AJNeufeld and @YayPawSi. Using your solutions, I was able to make the program print. Revised Output:

0
1*
1*
This is a prime. 2
This is a prime. 3*
This is a prime. 5*
8
This is a prime. 13*
21*
34
55*
This is a prime. 89*
144
This is a prime. 233*
377*
610
987*
This is a prime. 1597*
2584
4181*

回答1:

This is ArrayIndexOutOfBoundException,

    //Remove = sign for n < FibPrimes.length
    for (int n = 0; n < FibPrimes.length; n++){
            if (FibNums[i] == FibPrimes[n]){
                System.out.print(" " + "This is a prime.");
            }
     }

来源：https://stackoverflow.com/questions/46996036/how-to-print-a-text-notification-beside-prime-fibonacci-numbers

标签

java

arrays

loops

primes

fibonacci