Randomizing text file read in Java

Question

I am trying to read a text file in Java, basically a set of questions. With four choices and one answer. The structure looks like this:

question

option a

option b

option c

option d

answer

I have no trouble reading it that way:

public class rar{
public static String[] q=new String[50];
public static String[] a=new String[50];
public static String[] b=new String[50];
public static String[] c=new String[50];
public static String[] d=new String[50];
public static char[] ans=new char[50];
public static Scanner sr= new Scanner(System.in);


public static void main(String args[]){
int score=0;
try {
             FileReader fr;
      fr = new FileReader (new File("F:\\questions.txt"));
      BufferedReader br = new BufferedReader (fr);
int ar=0;
      for(ar=0;ar<2;ar++){
      q[ar]=br.readLine();
      a[ar]=br.readLine();
      b[ar]=br.readLine();
      c[ar]=br.readLine();
      d[ar]=br.readLine();
    String tempo=br.readLine();
    ans[ar]=tempo.charAt(0);
    
      
      
      
    
      
        System.out.println(q[ar]);
        System.out.println(a[ar]);
        System.out.println(b[ar]);
        System.out.println(c[ar]);
        System.out.println(d[ar]);
        System.out.println("Answer: ");
        String strans=sr.nextLine();
char y=strans.charAt(0);
if(y==ans[ar]){
    System.out.println("check!");
score++;
System.out.println("Score:" + score);
}else{
System.out.println("Wrong!");
}
        
      }
      br.close();
    } catch (Exception e) { e.printStackTrace();}


}

 


}

The code above is predictable. The for loop just increments. And it displays the questions based on order.

What I want to do is to be able to randomize through the text file, but still maintaining the same structure. (q, a, b, c, d, ans). But when I try to do this:

int ran= random(1,25);
   System.out.println(q[ran]);
        System.out.println(a[ran]);
        System.out.println(b[ran]);
        System.out.println(c[ran]);
        System.out.println(d[ran]);
        System.out.println("Answer: ");
        String strans=sr.nextLine();
char y=strans.charAt(0);
if(y==ans[ran]){
    System.out.println("check!");
score++;
System.out.println("Score:" + score);
}else{
System.out.println("Wrong!");
}

And this is the method that I use for randomizing:

public static int random(int min, int max){
    int xx;
    xx= (int) ( Math.random() * (max-min + 1))+ min;
    return xx;
    }

There's the possibility that I get a null. What can you recommend that I would do so that I get no null when trying to randomize the questions?

Can you see anything else that is wrong with my program?

Answer 1

I think a little structural changes will help a lot and make this much easier for you. Define new classes: Question and Answer. Let Question have the options and Answer inside of it. That's object composition.

Look into the Collection API. With a Collection of Questions, you can use the shuffle method to randomize them in one line. Let Java do the work for you.

So you might have:

Collection<Question> questions = new ArrayList<Question>();

questions.add(...);
questions.add(...);
questions.add(...);

questions.shuffle();

To embellish a little more about why you would want to do it this why... You want to separate your concerns the best you can. Questions, answers, and options are all different concerns. The user's response is a concern. The randomization of the questions is a concern. The response to the user's response is a concern.

Being a good software developer, you're going to want to compartmentalize all of these things. Java's construct for accomplishing this is the Class. You can develop your ideas relatively independently inside their own class. When you're satisfied with your Classes, all you have to do is connect them. Define their interfaces, how they talk to each other. I like to define the interfaces first, but when I started out, I found it a little easier to worry about that later.

Might seem like a lot of work, with all of these Classes and interfaces and what not. It'll take a fraction of the time to do it this way when you get good. And your reward is testability reusability.