FileReader and FileWriter
- Java course
- Intermediate
- Lesson 71/116
- 5 min
Learn to read and write text with FileReader and FileWriter.
Writing with FileWriter
The FileWriter class writes character by character. FileWriter w = new FileWriter("a.txt"); opens the file in write mode; it creates the file if missing, and truncates if it exists. w.write("Hello"); writes the text, w.close(); releases the resource.
FileWriter uses the system encoding by default. For correct Turkish characters, prefer new FileWriter("a.txt", StandardCharsets.UTF_8). You must call close() after writing; otherwise data may not reach disk.
Reading with FileReader
FileReader reads character by character. FileReader r = new FileReader("a.txt"); opens the file in read mode. r.read() returns the Unicode code of one character per call; at end of file it returns -1.
Reading single characters is inefficient; you usually wrap it in a BufferedReader. But for small files, direct FileReader is fine. After reading, r.close() is required.
Practice Write to a file with FileWriter
Import java.io.FileWriter and java.io.IOException. Add throws IOException to main. Create a FileWriter w = new FileWriter("hello.txt");, call w.write("Hello file");, close with w.close();. Finally print System.out.println("Written");.
Starter code
import java.io.FileWriter;
import java.io.IOException;
public class Main {
public static void main(String[] args) throws IOException {
// Create FileWriter, write, close
// Print Written
}
}Sample solution
import java.io.FileWriter;
import java.io.IOException;
public class Main {
public static void main(String[] args) throws IOException {
FileWriter w = new FileWriter("hello.txt");
w.write("Hello file");
w.close();
System.out.println("Written");
}
}Expected output
Written
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Complete the write call
FileWriter w = new FileWriter("a.txt");
w.____("Hello");
w.close();FileWriter w = new FileWriter("a.txt");
w.write("Hello");
w.close();Explanation: The write method writes text to the file.
2 What does FileReader.read() return at end of file?
- -1 Correct answer
- null
- 0
- An empty string
Explanation: read() returns -1 at end of file; this is used in loop conditions.
3 Match the Reader/Writer classes
| Term | Meaning |
|---|---|
FileWriter |
Writes character by character |
FileReader |
Reads character by character |
write() |
Writes text to the file |
read() |
Reads one character's code |