Reading Files

Intermediate ~15 min read

Reading data from files is a common task. Java provides multiple ways to do this, from the classic BufferedReader to the modern Files class.

Using BufferedReader (Classic Way)

It reads text from a character-input stream, buffering characters so as to provide for the efficient reading of characters, arrays, and lines.

try (BufferedReader br = new BufferedReader(new FileReader("file.txt"))) {
    String line;
    while ((line = br.readLine()) != null) {
        System.out.println(line);
    }
} catch (IOException e) {
    e.printStackTrace();
}

Full Example

import java.io.FileReader;
import java.io.IOException;

public class IoReading {
    public static void main(String[] args) {
        // Reading character by character
        try {
            FileReader reader = new FileReader("sample.txt");
            int character;
            System.out.println("Reading character by character:");
            while ((character = reader.read()) != -1) {
                System.out.print((char) character);
            }
            reader.close();
            System.out.println("\n\nReading completed!");
        } catch (IOException e) {
            System.out.println("Error reading file: " + e.getMessage());
        }
        
        // Reading into a character array
        try {
            FileReader reader = new FileReader("sample.txt");
            char[] buffer = new char[1024];
            int charactersRead;
            System.out.println("\nReading into buffer:");
            while ((charactersRead = reader.read(buffer)) != -1) {
                System.out.print(new String(buffer, 0, charactersRead));
            }
            reader.close();
        } catch (IOException e) {
            System.out.println("Error reading file: " + e.getMessage());
        }
    }
}

Output

Click Run to execute your code

Previous File Class

Next Writing Files →

Using BufferedReader (Classic Way)

Full Example

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