Java write to file. Using a loop

Question

I have a simple application that yet would trash a text file (it\'s just practice) I\'m only 3 days with Java yet. Problem is there are no errors until you run the program then

Answer 1

FileWriter file = new FileWriter("hello.txt");
    String sb =  " ";

   for (int i = 0; i < 1; i++) {
        sb += alphabet.charAt(r.nextInt(N));
        System.out.println(sb);
        int length = sb.length();
        file.write(sb);
        file.close();
        if(length == 30){
            sb = " ";
        }
    }

You are initializing FileWriter once and closing it in the 1st iteration itself then trying to use it again in next iteration. Hence you are getting an Exception.

I recommend put your for loop in try statement and close your FileWriter in finally statement. Here is oracle tut on try-catch-finally construct.

Final code will go something like below

    FileWriter file = null;
    try {
        try {
            file = new FileWriter("hello.txt");
            String sb = " ";
            for (int i = 0; i < 1; i++) {
                sb += alphabet.charAt(r.nextInt(N));
                System.out.println(sb);
                int length = sb.length();
                file.write(sb);
                if (length == 30) {
                    sb = " ";
                }
            }
        } finally {
            file.close();
        }
    } catch (IOException e) {
        e.printStackTrace();
    }