Thread: Rereading a Text File in Java

Due to my inexperience in Java (I've only been learning it for the past two months for school), I have come across an issue.

I was making this "insulting machine" program for one of my friends, as a joke. The program refers to a text file and finds how many lines it has. It then generates a number from 1-the max line number and stores all the text in an array and prints out the text in that line number. The user can also create insults, and it updates the text file with the new insult.

When I now run the insulting part of it, (I'm using a BufferedReader, maybe there is a simpler way?) and its position is still at the bottom of the text file, and I cannot find a way to reread the text file again to update the array. If I go back to the insulting part, it prints out NULL as I've reached the end of the file. Any ideas on how to fix this please?

(I do realize my code may not be the most efficient, I've only started to program)

Thank you in advance

import java.util.Scanner;
    import java.io.*;
    import java.util.Random;
    public class InsultingMachine{
        public static void main(String args[]) throws IOException{
            File insult = new File("insults.txt");
            boolean exist = insult.exists();
 
            if(exist == false){
                System.out.println("The file does not exist, creating the file...?");
                PrintWriter writer = new PrintWriter("insults.txt", "UTF-8");
                writer.close();
                System.out.println("Done");
            }
 
 
            //objects
            Scanner input = new Scanner(System.in);
            Scanner inputIn = new Scanner(System.in);
            Scanner inputIn2 = new Scanner(System.in);
            Random ranGen = new Random();
            BufferedReader reader = new BufferedReader(new FileReader("insults.txt"));
            BufferedReader reader2 = new BufferedReader(new FileReader("insults.txt"));
            BufferedWriter wr = new BufferedWriter(new FileWriter("insults.txt", true));
 
            //vars
            int i, ranInt;
            int lineNum = 0;
            int lineNum2 = 0;
            int counter = 0, counter2 = 0, counter3 = 0, menuCounter = 0;
            String outputting;
            String s1, s2;
 
 
 
            while (menuCounter == 0){
                System.out.println("Hello, please select an option from the menu: ");
 
                System.out.println("(1) INSULTS");
                System.out.println("(2) Create insults");
                System.out.println("(3) Exit");
 
                i = input.nextInt();
 
                switch(i){
                    case 1:
                        //Establish Line Number
 
                        while(reader.readLine() != null){
                            lineNum++;
                        }
                        //store the lines of the text file
                        String L[] = new String[lineNum];
 
                        lineNum2 = 0;
                        while(lineNum2 < lineNum){
                            L[lineNum2] = reader2.readLine();
                            lineNum2++;
                        }
 
                        System.out.println("You may start you fool...Enter an insult --type exit to exit-- :");
                        while (counter == 0){
                            s2 = inputIn.nextLine();
 
                            if(s2.equalsIgnoreCase("exit")){
                                break;
                            }
 
                            //generate number from 1 to max line number
                            ranInt = ranGen.nextInt(lineNum);
                            if (ranInt == 0)
                            {
                                ++ranInt;
                            }
 
                            System.out.println(L[ranInt]);
                        }
                        break;
 
                    case 2:
                        while(counter3 == 0){
                            System.out.println("Please enter the insult you would like to add --type exit to exit-- : ");
                            s2 = inputIn2.nextLine();
 
                            if(s2.equalsIgnoreCase("exit"))
                            {
                                wr.close();
                                break;
                            }
                            wr.newLine();
                            wr.write(s2);
 
 
                        }
                        break;
 
                    case 3:
                        menuCounter++;
                        break;
                    default:
                        System.out.println("Please enter a correct value...");
                        break;
 
                }
            }
        }
    }

Why are you re-reading the file rather than just using the array in which the file contents have already been stored?

If the user decides to add in an entry, I need to update the file contents, so I reread the file to get the new entry added (if that makes sense?)

--- Update ---

And I don't think that I can append the array, and as I just learned how to use the IO, I'm not entirely sure how to go about this issue

I suggest using one array to hold the file contents, another array to hold the user's changes, and then write both arrays to the file when the program exits. As data is needed while the program is running, access it from the arrays, not the file.