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I'm making some really simple program in java just to see how I/O works, but I have a problem. I've created"test.txt" file, and now I'm trying to (over Scanner) enter username and password every time when I start program, which is not big deal. I made my program read content from file and write to console. But, my problem is, I want that every time I run program and enter new username that my program go through the file, read every username and give me a warning if username already exist.

Stojanic
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    Possible duplicate of [Java: How to read a text file](http://stackoverflow.com/questions/2788080/java-how-to-read-a-text-file) – byxor Jan 09 '17 at 15:57
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  • Specifically, if you're asking with help with your code, you need to include that code in your question along with the inputs, expected vs actual outputs, any errors, etc. Ideally include a [mcve]. – azurefrog Jan 09 '17 at 15:58

1 Answers1

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Not sure if this is what you're looking for but this should do the job. It's a quick simple solution.

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.Scanner;

public class Test {

    public static void main(String[] args) {

        String filePath = "{YOUR_FILEPATH_TO_TEST.TXT}";
        Scanner scanner = new Scanner(System.in);
        System.out.println("Enter your username: ");
        String username = scanner.nextLine();
        System.out.println("Checking to see if username exists...");
        BufferedReader bufferedReader;
        try {
            bufferedReader = new BufferedReader(new FileReader(filePath));
            String line;
            boolean usernameExists = false;
            while((line = bufferedReader.readLine()) != null) {
                if (line.equals(username)) {
                    usernameExists = true;
                    break;
                }
            }
            if (usernameExists) {
                System.out.println("Username exists! Please try again.");
            } else {
                System.out.println("Username accepted");
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

}
ubiquitous23
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