How to Use Java IO to Copy One File to Another

Question

How can I copy a file to another location using Java IO?

import java.io.*;

public class FileCopy {
    public static void main(String[] args) {
        File sourceFile = new File("source.txt");
        File destFile = new File("destination.txt");
        copyFile(sourceFile, destFile);
    }

    public static void copyFile(File sourceFile, File destFile) {
        try (InputStream in = new FileInputStream(sourceFile);
             OutputStream out = new FileOutputStream(destFile)) {
            byte[] buffer = new byte[1024];
            int length;
            while ((length = in.read(buffer)) > 0) {
                out.write(buffer, 0, length);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Answer

Copying files in Java can be performed easily using the java.io package. This process typically involves reading the source file and writing its contents to the destination file using Input and Output streams.

import java.io.*;

public class FileCopy {
    public static void main(String[] args) {
        File sourceFile = new File("source.txt");
        File destFile = new File("destination.txt");
        copyFile(sourceFile, destFile);
    }

    public static void copyFile(File sourceFile, File destFile) {
        try (InputStream in = new FileInputStream(sourceFile);
             OutputStream out = new FileOutputStream(destFile)) {
            byte[] buffer = new byte[1024];
            int length;
            while ((length = in.read(buffer)) > 0) {
                out.write(buffer, 0, length);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Causes

The source file may not exist.
Insufficient permissions to read/write files.
Target directory might not exist.

Solutions

Ensure the source file exists and the path is correct.
Check file permissions for reading/writing.
Create the target directory if it does not exist before copying.

Common Mistakes

Mistake: Not handling exceptions correctly.

Solution: Use try-catch blocks to manage IOExceptions appropriately.

Mistake: Assuming the file paths are correct.

Solution: Verify that file paths are accurate by checking their existence before copying.

Mistake: Overwriting files without warning.

Solution: Check if the destination file exists and prompt the user if they want to overwrite it.

Helpers

Java IO
file copy Java
copy file in Java
Java file handling