如何在循环迭代开始时获取新的随机数 Java

Question

I'm fairly new to coding and as a project I'm trying to create a question and answer program for practical use. In theory, what this program should do is ask you for how many questions you want then give you a random selection of questions and the corresponding answer to the questions. Through each iteration of the loop it should give you a new question and answer but for some reason it repeatedly gives the same question and answer. Any help would be highly appreciated.

Random rand = new Random();
    int int_random = rand.nextInt(6);
    int storage = int_random;

    String[] questionV = {"Question 1", "Question 2", "Question 3", "Question 4", "Question 5"};
    String[] answerV = {"Answer 1", "Answer 2", "Answer 3", "Answer 4", "Answer 5",};

   public void question_answerV() {

        System.out.println("How many questions would you like? (1-5) ");
        Scanner scanner = new Scanner(System.in);
        int choice = scanner.nextInt();

        switch (choice) {
            case 1:
                System.out.println(questionV[int_random]);
                System.out.println("Please press any number for the answer");
                Scanner scanner1 = new Scanner(System.in);
                int choiceA = scanner1.nextInt();
                System.out.println(answerV[storage]);
                break;

            case 2:
                for (int i = 0; i < 2 ; i++ ) {
                    System.out.println(questionV[int_random]);
                    System.out.println("Please press any number for the answer");
                    scanner1 = new Scanner(System.in);
                    choiceA = scanner1.nextInt();
                    System.out.println(answerV[storage]);
                }
                break;

            case 3:
                for (int i = 0; i < 3 ; i++ ) {
                    System.out.println(questionV[int_random]);
                    System.out.println("Please press any number for the answer");
                    scanner1 = new Scanner(System.in);
                    choiceA = scanner1.nextInt();
                    System.out.println(answerV[storage]);
                }
                break;

            case 4:
                for (int i = 0; i < 4 ; i++ ) {
                    System.out.println(questionV[int_random]);
                    System.out.println("Please press any number for the answer");
                    scanner1 = new Scanner(System.in);
                    choiceA = scanner1.nextInt();
                    System.out.println(answerV[storage]);
                }
                break;

            case 5:
                for (int i = 0; i < 5 ; i++ ) {
                    System.out.println(questionV[int_random]);
                    System.out.println("Please press any number for the answer");
                    scanner1 = new Scanner(System.in);
                    choiceA = scanner1.nextInt();
                    System.out.println(answerV[storage]);
                }
                break;
        }
    }

Answer 1

Some observations.

• As already mentioned, use only one Scanner instance.
• You are also repeating code. Just use the choice (that you switch on) as the loop terminating value
• look at the following code:
  • int_random never changes.
  • you prompt for choiceA but never use it
  • since you initialized storage to int_random at the beginning, you will always get the same q and a .

for (int i = 0; i < 4 ; i++ ) {
  System.out.println(questionV[int_random]);
  System.out.println("Please press any number for the answer");
  scanner1 = new Scanner(System.in);
  choiceA = scanner1.nextInt();
  System.out.println(answerV[storage]);
}

If (and it's not clear) you want to select questions and answers randomly.

• initialize an ArrayList from 0 to n choice as appropriate.

• Call Collections.shuffle(list) to randomize the list.

• then just choose a question number from the list starting with 0, 1, 2... using list.get(). Use the obtained number for the question and answer. None will be repeated.

• And I recommend a little defensive programming. Make certain that choice is within the bounds of the array of questions. If not, let the user know and reprompt. Otherwise you could get an ArrayIndexOutOfBoundsException .