Copy Content/ Data From One File to Another in Java

In Java, copying data from one file to another file is a very simple process. We use the File, FileInputStream, and FileOutputStream classes for copying data. Before implementing the code, let's understand all these three classes one by one.

File

File class is used to create an instance of the file from which we want to write or read bytes of data. We create an instance of the File class in the following way:

We pass the filename in which we want to perform the read/write operation. If the specified file doesn't exist, it creates a new file with the specified name.

FileInputStream Class

The FileInputStream is one of the most used and important byte input stream classes in Java. It is mainly used for reading bytes of data from a file. FileInputStream class provides several methods for reading data from the file.

We create an instance of the FileInputStream class in the following way:

We pass the file name to the constructor from which we want to read data.

We use the following two methods of the FileInputStream class for copying data from one file to another one.

read() method
The read() method plays an important role in reading data from the file. It returns bytes data as an integer, and when its pointer reaches the end of the file, it returns -1.
close() method
The close() method is used for closing the instance of the FileInputStream class.

FileOutputStream Class

The FileOutputStream is one of the most used and important byte output stream classes in Java. It is mainly used for writing bytes data into a file. FileOutputStream class provides several methods for writing data into the file.

We create an instance of the FileOutputStream class in the following way:

We pass the file name to the constructor in which we want to write data.

We use the following two methods of the FileOutputStream class for copying data from one file to another one.

write() method
The write() method plays an important role in writing data(bytes data) into the file
close() method
The close() method is used for closing the instance of the FileOutputStream class.

Let's implement the code for copying data from one file to another by using File, FileInputStream, and FileOutputStreamclasses.

FileExample.java

// import required classes and packages
packagejavaTpoint.javacodes;
import java.io.*;
importjava.util.*;
// create FileExample class to copy data of one file into another
publicclassFileExample {
	// create coptData() method that copy data of file1 into file2
	publicstaticvoidcopyData(File file1, File file2) throws Exception
	{
		// create instances of FileInputStream and FileOutputStream classes for file1 and file2
		FileInputStreaminputStream = newFileInputStream(file1);
		FileOutputStreamoutputStream = newFileOutputStream(file2);
		// use try-catch-finally block to read and write bytes data into file
		try {
			// declare variable for indexing
			inti;
			// use while loop with read() method of FileInputStream class to read bytes data from file1
			while ((i = inputStream.read()) != -1) {
				
				// use write() method of FileOutputStream class to write the byte data into file2
				outputStream.write(i);
			}
		}
		// catch block to handle exceptions
		catch(Exception e) {
			System.out.println("Error Found: "+e.getMessage());
		}
		// use finally to close instance of the FileInputStream and FileOutputStream classes
		finally {
			if (inputStream != null) {
		// use close() method of FileInputStream class to close the stream
				inputStream.close();
			}
			// use close() method of FileOutputStream class to close the stream
			if (outputStream != null) {
				outputStream.close();
			}
		}
		System.out.println("File Copied");
	}
	// main() method start
	publicstaticvoid main(String[] args) throws Exception
	{
		// create scanner class object to take file name from user
		Scanner sc = newScanner(System.in);
		// get the file from which the data would be copied.
		System.out.println("Enter the name of the file from where the data would be copied :");
		String file1 = sc.nextLine();
		// create instance of the File class for the source file 
		File a = newFile("C:\\Users\\pc\\OneDrive\\Desktop\\"+file1);

		// get the file in which the data would be written.
		System.out.println("Enter the name of the file from where the data would be written :");
		String file2 = sc.nextLine();
		// create instance of the File class for the destination file
		File b = newFile("C:\\Users\\pc\\OneDrive\\Desktop\\"+file2);
		sc.close();
		// method called to copy the data from file a to file b
		copyData(a, b);
	}
}

Output: