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Here’s a complete file downloader example program with output, error checking, and command line argument checks:

package so.downloader;

import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URI;
import java.nio.file.Files;
import java.nio.file.Paths;

public class Application {
    public static void main(String[] args) throws MalformedURLException, IOException {
        if (2 != args.length) {
            System.out.println(String.format("USAGE: java -jar so-downloader.jar <source-URL> <target-filename>"));
            System.exit(1);
        }

        String sourceUrl = args[];
        String targetFilename = args[1];

        long bytesDownloaded = download(sourceUrl, targetFilename);

        System.out.println(String.format("Downloaded %d bytes from %s to %s.", bytesDownloaded, sourceUrl, targetFilename));
    }

    static long download(String sourceUrl, String targetFileName) throws MalformedURLException, IOException {
        try (InputStream in = URI.create(sourceUrl).toURL().openStream()) {
            return Files.copy(in, Paths.get(targetFileName));
        }
    }

}

As noted in the so-downloader repository README:

To run file download program:

java -jar so-downloader.jar <source-URL> <target-filename>

for example:

java -jar so-downloader.jar https://github.com/JanStureNielsen/so-downloader/archive/main.zip so-downloader-source.zip

When using Java 7+ use the following method to download a file from the Internet and save it to some directory:

private static Path download(String sourceURL, String targetDirectory) throws IOException
{
    URL url = new URL(sourceURL);
    String fileName = sourceURL.substring(sourceURL.lastIndexOf('/') + 1, sourceURL.length());
    Path targetPath = new File(targetDirectory + File.separator + fileName).toPath();
    Files.copy(url.openStream(), targetPath, StandardCopyOption.REPLACE_EXISTING);

    return targetPath;
}

Documentation here.

Another method shown here

public static void downloadFileFromURL(String urlString, File destination) {    
        try {
            URL website = new URL(urlString);
            ReadableByteChannel rbc;
            rbc = Channels.newChannel(website.openStream());
            FileOutputStream fos = new FileOutputStream(destination);
            fos.getChannel().transferFrom(rbc, , Long.MAX_VALUE);
            fos.close();
            rbc.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

Another Complete java program to download file from server

import java.io.*;
import java.net.*;

public class filedown {
    public static void download(String address, String localFileName) {
        OutputStream out = null;
        URLConnection conn = null;
        InputStream in = null;

        try {
            URL url = new URL(address);
            out = new BufferedOutputStream(new FileOutputStream(localFileName));
            conn = url.openConnection();
            in = conn.getInputStream();
            byte[] buffer = new byte[1024];

            int numRead;
            long numWritten = ;

            while ((numRead = in.read(buffer)) != -1) {
                out.write(buffer, , numRead);
                numWritten += numRead;
            }

            System.out.println(localFileName + "\t" + numWritten);
        } 
        catch (Exception exception) { 
            exception.printStackTrace();
        } 
        finally {
            try {
                if (in != null) {
                    in.close();
                }
                if (out != null) {
                    out.close();
                }
            } 
            catch (IOException ioe) {
            }
        }
    }

    public static void download(String address) {
        int lastSlashIndex = address.lastIndexOf('/');
        if (lastSlashIndex >=  &&
        lastSlashIndex < address.length() - 1) {
            download(address, (new URL(address)).getFile());
        } 
        else {
            System.err.println("Could not figure out local file name for "+address);
        }
    }

    public static void main(String[] args) {
        for (int i = ; i < args.length; i++) {
            download(args[i]);
        }
    }
}