Question

I am new to Java and trying to solve the problem below

So this is my story:
Program generates 20 numbers up to 100 and stores every number in array. Once generated the program has to add two numbers and stores the answer in array.. Example

randomNumber[0]+randomNumber[1]=answer[0]
randomNumber[2]+randomNumber[3]=answer[1]
randomNumber[4]+randomNumber[5]=answer[2]

etc..

Once done I check user input with answers and count the correct answers.

The problem is: I can’t figure out how to add two numbers together and store it in Array. It seems easy but I am not experienced enough 🙂

Currently I am stuck here, I would really appreciate if someone could explain or help me how to solve this problem.

public class gNumber {
    private final int[] num = new int[20]; // array of randomly generated numbers
    private int[] answers; // array of correct answers and UserAnswers
    private final int[] userAnswers = new int[10];
    private int numOfCorrect = 0;

    // Accessor to get the randomly generated number
    int getNumbers(final int n) {
        return num[n];
    }

    int numOfCorrectAnswers() {
        return numOfCorrect;
    }

    // Mutator to store store user input
    void setUsrAnswers(final int _index, final int answer) {
        userAnswers[_index] = answer;
    }

    // Method to generate random 20 numbers
    public void RandomN() {

        for (int i = 0; i < num.length; i++) {
            final int randomNum = (int) (Math.random() * 100);
            num[i] = randomNum;
            final int a = num[i];
            // int b =num[i];
            answers[i] = a + a;
            System.out.println(i + ")" + num[i] + answers[i]);
        }

    }

    // method to add two numbers and store in in answers array
    public void add(int arg1, int arg2) {
        int b = 0;
        while (b < 10) {
            arg1 = num[b];
            arg2 = num[b + 1];
            answers[b] = arg1 + arg2;

            System.out.println(answers[b]);
            b = b + 1;
        }
    }

    // method to check user answers
    public void usrInput(final int usrAnwer) {
        for (final int num : answers) {
            if (num == usrAnwer) {
                numOfCorrect++;
            }
        }

    }
}

Answer 1

A solution quite simply:

int N = 20; //20 Random numbers
int[] randomNumber = new int[N];
int[] answer = new int[N/2];

//Generate random numbers of size N
for (int i = 0; i < N; i++) {
    randomNumber = generateRandom(0, 100);
}

//populate answers
for (int i = 0; i < answer.length; i++) {
    answer[i] = randomNumber[i*2] + randomNumber[i*2 + 1];
}

//Generate a random number from [min, max]
private int generateRandom(int min, int max) {
    return min + (int)(Math.random() * ((max - min) + 1));
}

The explanations are on the comments. 🙂