为什么我的代码不会随机生成多次？

Question

Sorry for probably a noobish question but I can't figure out what's wrong with this code. I've looked everywhere but I couldn't find any answer.

The problem is that it will only randomly generate num and num2 once when I need it randomly genereated 5 times. Any help is greatly appreciated.

import java.util.Scanner;

import java.util.Random;

public class Choice5
{
    public static void main(String [] args)
    {
        Random r = new Random();
        Scanner k = new Scanner(System.in);
        String name;

        int num= 1 + r.nextInt(10);
        int num2=1 + r.nextInt(10);

        int answer = num*num2;
        int attempt;
        int countcorrect = 0;
        int countincorrect =0;

        System.out.println("Hi, what's your name?");
        name =k.next();

        for(int x=1; x<=5; x++)
        {
            System.out.println("Test " +x+ " of 5");
                System.out.println("Ok " +name+ " What is " +num+ " x " +num2+ " ?");
                attempt = k.nextInt();

                if(attempt == answer)
                {
                    System.out.println("Good Job " +name+ " the answer was indeed " +answer);
                    countcorrect++;
                }
                if(attempt != answer)
                {
                    System.out.println("Incorrect " +name+ " the answer was actually " +answer);
                    countincorrect++;
                }
        }
                System.out.println("You got " +countcorrect+ " right");
                System.out.println("You got " +countincorrect+ " wrong");
                if (countcorrect < 3)
                {
                    System.out.println("You should try the test again");
                }
                else
                {
                    System.out.println("Good job " +name+ " ,you passed the test!");
                }

    }
}

Answer 1

You are choosing random numbers for num and num2 exactly once, toward the top of main , and more importantly, before the for loop. These numbers aren't assigned again, so they remain the same during all loop iterations.

To have them change for each loop iteration, declare the variables for the numbers and the answer, and assign new values inside the for loop, instead of before it.

for(int x=1; x<=5; x++)
{
    int num= 1 + r.nextInt(10);
    int num2=1 + r.nextInt(10);
    int answer = num*num2;
    // rest of code is the same

Answer 2

You generate a random number when, in this case, you call nextNum() As you can see you only call this once for num and num2 since it is out of the loop.

Simple answer, put those calls within your loop to create more than one random number.