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Java IO & NIO - Files.copy() Examples

[Last Updated: Oct 30, 2025]

Java IO & NIO Java Java API 

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Class:

java.nio.file.Files

java.lang.Objectjava.lang.Objectjava.nio.file.Filesjava.nio.file.FilesLogicBig

Methods:

public static Path copy(Path source,
                        Path target,
                        CopyOption... options)
                 throws IOException

This method copies a file to the target file.

Parameters:
source - the path to the file to copy
target - the path to the target file
options - options specifying how the copy should be done
Returns:
the path to the target file



public static long copy(InputStream in,
                        Path target,
                        CopyOption... options)
                 throws IOException

Copies all bytes from an input stream to a file.

Parameters:
in - the input stream to read from
target - the path to the file
options - options specifying how the copy should be done
Returns:
the number of bytes read or written



public static long copy(Path source,
                        OutputStream out)
                 throws IOException

Copies all bytes from a file to an output stream.

Parameters:
source - the path to the file
out - the output stream to write to
Returns:
the number of bytes read or written


Examples


package com.logicbig.example.files;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardCopyOption;

public class CopyExample {

    public static void main(String... args) throws IOException {
        Path tempFile = Files.createTempFile("my-file", ".txt");
        System.out.println("file to copy: " + tempFile);
        Path copiedFile = Files.copy(
                tempFile,
                Paths.get("C:\\temp\\" + tempFile.getFileName()),
                StandardCopyOption.REPLACE_EXISTING
        );
        System.out.println("file copied: " + copiedFile);
        System.out.println("copied file exits: " + Files.exists(copiedFile));
    }
}

Output

file to copy: C:\Users\Joe\AppData\Local\Temp\my-file5278968784931578089.txt
file copied: C:\temp\my-file5278968784931578089.txt
copied file exits: true




package com.logicbig.example.files;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardCopyOption;

public class CopyExample2 {

    public static void main(String... args) throws IOException {
        InputStream inputStream = new ByteArrayInputStream("test string".getBytes());
        System.out.println("inputStream bytes available: " + inputStream.available());
        Path target = Paths.get("C:\\temp\\copy-file-test.txt");

        long bytesCopied = Files.copy(
                inputStream,
                target,
                StandardCopyOption.REPLACE_EXISTING
        );
        System.out.println("file copied: " + target);
        System.out.println("copied file exits: " + Files.exists(target));
        System.out.println("bytes copied: " + bytesCopied);
        System.out.println("copied file size: " + Files.size(target));
    }
}

Output

inputStream bytes available: 11
file copied: C:\temp\copy-file-test.txt
copied file exits: true
bytes copied: 11
copied file size: 11




package com.logicbig.example.files;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;

public class CopyExample3 {

    public static void main(String... args) throws IOException {
        Path source = Files.createTempFile("copy-test-src-fle", ".txt");
        Files.write(source, "some test content".getBytes());
        System.out.println("Source file: " + source);
        System.out.println("Source file size: " + Files.size(source));
        //An outputStream
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        //copying now
        long bytesCopied = Files.copy(source, outputStream);
        System.out.println("Bytes copied: " + bytesCopied);
        System.out.println("Content copied: " + new String(outputStream.toByteArray()));
    }
}

Output

Source file: C:\Users\Joe\AppData\Local\Temp\copy-test-src-fle9127021129324648119.txt
Source file size: 17
Bytes copied: 17
Content copied: some test content

See Also