Java Write to Files

📝 Java Write to Files

Java provides several ways to write data to files using:

FileWriter
BufferedWriter
PrintWriter
Files.write() (modern method)
FileOutputStream (for binary data)

1. Using `FileWriter` (Simple Text Writing)

import java.io.FileWriter;
import java.io.IOException;

public class WriteFileExample {
public static void main(String[] args) {
try {
FileWriter writer = new FileWriter("example.txt");
writer.write("Hello, this is written using FileWriter!");
writer.close();
System.out.println("Successfully wrote to the file.");
} catch (IOException e) {
System.out.println("An error occurred.");
}
}
}

import java.io.FileWriter;

import java.io.IOException;

public class WriteFileExample {

public static void main(String[] args) {

try {

FileWriter writer = new FileWriter("example.txt");

writer.write("Hello, this is written using FileWriter!");

writer.close();

System.out.println("Successfully wrote to the file.");

} catch (IOException e) {

System.out.println("An error occurred.");

}

🧩 Appending Instead of Overwriting

To append content, pass true as the second argument:

2. Using `BufferedWriter` (Faster for Large Text)

import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;

public class BufferedWriterExample {
public static void main(String[] args) {
try (BufferedWriter bw = new BufferedWriter(new FileWriter("buffered.txt"))) {
bw.write("This is written using BufferedWriter!");
bw.newLine();
bw.write("It is faster for large files.");
} catch (IOException e) {
System.out.println("Error while writing.");
}
}
}

import java.io.BufferedWriter;

import java.io.FileWriter;

import java.io.IOException;

public class BufferedWriterExample {

public static void main(String[] args) {

try (BufferedWriter bw = new BufferedWriter(new FileWriter("buffered.txt"))) {

bw.write("This is written using BufferedWriter!");

bw.newLine();

bw.write("It is faster for large files.");

} catch (IOException e) {

System.out.println("Error while writing.");

}

3. Using `PrintWriter` (Easy Formatting)

import java.io.PrintWriter;

public class PrintWriterExample {
public static void main(String[] args) {
try (PrintWriter pw = new PrintWriter("printwriter.txt")) {
pw.println("Hello using PrintWriter!");
pw.println("Number: " + 100);
pw.printf("Formatted text: %.2f", 45.678);
} catch (Exception e) {
System.out.println("Error writing.");
}
}
}

import java.io.PrintWriter;

public class PrintWriterExample {

public static void main(String[] args) {

try (PrintWriter pw = new PrintWriter("printwriter.txt")) {

pw.println("Hello using PrintWriter!");

pw.println("Number: " + 100);

pw.printf("Formatted text: %.2f", 45.678);

} catch (Exception e) {

System.out.println("Error writing.");

}

4. Using `Files.write()` (Modern Java NIO)

This is the easiest and preferred method in Java 7+.

import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.Arrays;

public class NioWriteExample {
public static void main(String[] args) {
try {
Files.write(Paths.get("nio.txt"), "Hello NIO File Write!".getBytes());
} catch (Exception e) {
System.out.println("Error writing file.");
}
}
}

import java.nio.file.Files;

import java.nio.file.Paths;

import java.util.Arrays;

public class NioWriteExample {

public static void main(String[] args) {

try {

Files.write(Paths.get("nio.txt"), "Hello NIO File Write!".getBytes());

} catch (Exception e) {

System.out.println("Error writing file.");

}

Writing multiple lines:

5. Writing Binary Data (FileOutputStream)

Used for writing images, PDFs, or binary content.

import java.io.FileOutputStream;

public class BinaryWriteExample {
public static void main(String[] args) {
try (FileOutputStream fos = new FileOutputStream("binary.dat")) {
fos.write(new byte[] {65, 66, 67}); // Writes A, B, C
} catch (Exception e) {
System.out.println("Error writing binary.");
}
}
}

import java.io.FileOutputStream;

public class BinaryWriteExample {

public static void main(String[] args) {

try (FileOutputStream fos = new FileOutputStream("binary.dat")) {

fos.write(new byte[] {65, 66, 67}); // Writes A, B, C

} catch (Exception e) {

System.out.println("Error writing binary.");

}

🧠 Summary Table

Method	Best Use Case
`FileWriter`	Simple text writing
`BufferedWriter`	Writing large files with better performance
`PrintWriter`	Writing formatted text
`Files.write()`	Short and modern syntax
`FileOutputStream`	Binary data (images, files, audio)

✔ Good Practice

Always close the resource or use try-with-resources, like:

Java Write to Files