Java — How to copy a File or Directory | Code Factory

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You’ll learn how to copy a file or directory in Java using various methods like Files.copy() or using BufferedInputStream and BufferedOutputStream.

Java Copy File using Files.copy()

Java NIO’s Files.copy() method is the simplest way of copying a file in Java.

package com.example.java.programming.file;
import java.io.IOException;
import java.nio.file.FileAlreadyExistsException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
/**
 * @author code.factory
 *
 */
public class CopyFileExample {
	public static void main(String... args) {
		Path sourceFilePath = Paths.get("folder/folder1/test.txt");
		Path targetFilePath = Paths.get("folder/folder2/test.txt");
		try {
			Files.copy(sourceFilePath, targetFilePath);
			System.out.println("Done");
		} catch (FileAlreadyExistsException ex) {
			System.out.println("File already exists");
		} catch (IOException ex) {
			System.out.format("I/O error: %s%n", ex);
		}
	}
}

Output :

Done

The Files.copy() method will throw FileAlreadyExistsException if the target file already exists. If you want to replace the target file then you can use the REPLACE_EXISTING option like this -

Files.copy(sourceFilePath, targetFilePath, StandardCopyOption.REPLACE_EXISTING);

Java Copy File using BufferedInputStream and BufferedOutputStream

You can also copy a file byte-by-byte using a byte-stream I/O. The following example uses BufferedInputStream to read a file into a byte array and then write the byte array using BufferedOutputStream.

You can also use a FileInputStream and a FileOutputStream directly for performing the reading and writing. But a Buffered I/O is more performant because it buffers data and reads/writes it in chunks.

package com.example.java.programming.file;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
/**
 * @author code.factory
 *
 */
public class CopyFileExample {
	public static void main(String... args) {
		Path sourceFilePath = Paths.get("folder/folder1/test.txt");
		Path targetFilePath = Paths.get("folder/folder2/test.txt");
		try (InputStream inputStream = Files.newInputStream(sourceFilePath);
				BufferedInputStream bufferedInputStream = new BufferedInputStream(inputStream);
				OutputStream outputStream = Files.newOutputStream(targetFilePath);
				BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(outputStream)) {
			byte[] buffer = new byte[4096];
			int numBytes;
			while ((numBytes = bufferedInputStream.read(buffer)) != -1) {
				bufferedOutputStream.write(buffer, 0, numBytes);
			}
			System.out.println("Done");
		} catch (IOException ex) {
			System.out.format("I/O error: %s%n", ex);
		}
	}
}

Output :

Done