public static void main(String[] args) {
    String Question = null, Answer = null, Panswer = null, Continue = null, Type;
    int Looptimes, Nanswer = 0, PNanswer = 0, i = 0;
    boolean Flag = false;
    Scanner Input = new Scanner(System.in);
    System.out.println("How many times do you want to study this question?");
    Looptimes = Input.nextInt();
    System.out.println("What is the Question you need to study?");
    int c = 1 + 1;
    Question = Input.nextLine();
    System.out.println("What is the Answer to the Question?");
    Answer = Input.nextLine();
    System.out.flush();
    do {
        System.out.println(Question);
        System.out.println("What's the answer?");
        Panswer = Input.nextLine();
        if(Panswer.contentEquals(Answer)) {
            System.out.println("You're correct!! The answer is " + Answer);
            Flag = true;
        }else if(!Panswer.contentEquals(Answer)) {
            System.out.println("You're incorrect, the answer is " + Answer);
            Flag = false;
        }
        i++;
            do{
                if(i == Looptimes) {
                System.out.println("Do you want to continue?");
                Continue = Input.nextLine();
                if(Continue.contentEquals("Yes") || Continue.contentEquals("yes") || Continue.contentEquals("Yea") || Continue.contentEquals("Yeah") || Continue.contentEquals("Y") || Continue.contentEquals("y")) {
                    Flag = false;
                }
                else if(Continue.contentEquals("No") || Continue.contentEquals("no") || Continue .contentEquals("N") || Continue.contentEquals("n") || Continue .contentEquals("Nope") || Continue.contentEquals("nope")) {
                        System.out.println("Stopping Program");
                        Flag = true;
                }else{
                    System.out.println("Try Again!");
                    }
                }
            } while(!(Continue.contentEquals("Yes") || Continue.contentEquals("yes") || Continue.contentEquals("Yea") || Continue.contentEquals("Yeah") || Continue.contentEquals("Y") || Continue.contentEquals("y") || Continue.contentEquals("No") || Continue.contentEquals("no") || Continue .contentEquals("N") || Continue.contentEquals("n") || Continue .contentEquals("Nope") || Continue.contentEquals("nope")))
        }while(Flag = false || i != Looptimes)
        Input.close();
}
}

How many times do you want to study this question?
5
What is the Question you need to study?
What is the Answer to the Question?
w

What's the answer?
w
You're correct!! The answer is w
Exception in thread "main" java.lang.NullPointerException
    at StudyIdea.main(StudyIdea.java:42)