How do you append to a file?

[saytri]

Hi guys!
I am making a quiz. The questions are stored in a binary file. I made an option in the quiz where a user can add a question to the binary file. Altough this works, the problem is that whenever a user enters a new question is just overwrites the whole file, instead of adding it to the rest of the questions in the binary file. Do i have something wrong? Thanks a lot. :-)

This is the piece of code that adds a question to binary file:

try {
            
                     String question = JOptionPane.showInputDialog(null, "Enter new question");
     
     

                File aFile  = new File( "rocks.dat" );
   
               FileOutputStream aFileOutStream = new FileOutputStream ( aFile );
     
               DataOutputStream aDataOutStream = new DataOutputStream ( aFileOutStream );

     
              aDataOutStream.writeUTF( question );
     
              aFileOutStream.close();

                        
                        
                    
                    }catch(IOException event){
                   System.out.println("There was a problem:" + e);

                               }

[BigDaddyLH]

Please remember to provide a meaningful Title for any threads started (see the FAQ entry Use a Good Thread Title).

This helps to ensure that other members, and also the general public, will have a better chance of finding answers to any similar questions.

MODERATOR

[BigDaddyLH]

To append to a file, open the file for appending:

FileOutputStrea m(File file, boolean append)

[CODE=Java]FileOutputStrea m fos = new FileOutputStrea m (file, true);[/CODE]

[saytri]

Thanks a lot. And i'm really sorry about that. Next time i will use a more clear title for the thread. I have another problem, where i have to generate a set of questions stored in a binary file randomly. I used this method (code below), but the questions are repeating themselves. Is there another method i can use, instead of this, to generate the questions randomly, without popping up repetetive questions?

This is the code:

  public void askQuestions(String[] questions, String[] answers) {
      
        int count = 0;
        int point = 0;
        
        
       for(int j = 0; j < questions.length; j++) {
            
           timeForMore = true;
           
          
          Random generator = new Random();
          int randomIndex = generator.nextInt(questions.length); 
          String input = JOptionPane.showInputDialog(null, questions[randomIndex]); 

        
          if(answers[randomIndex].equalsIgnoreCase(input))
           
           count++;  // incrementing counter if entered answer is correct
           point++;
          
          
    if(!timeForMore) // if time is over, the program executes the loop an stops asking questions.
                break; 
     }
         
        JOptionPane.showMessageDialog(null, "You answered " + count +
                                      " out of " + questions.length +
                                      " questions correctly.");

            }

[BigDaddyLH]

To avoid repetition, take the questions and shuffle them, then loop though the shuffled questions. If you are familiar with the Collection Framework, you can pass a list to Collections.shu ffle:

Collections.shu ffle

If you are not familiar with the Collection Framework, I recommend learning it: it is one of the most useful parts of the API:

http://java.sun.com/docs/books/tutorial/collections/index.html