How to copy file from one location to another location?

Question

I want to copy a file from one location to another location in Java. What is the best way to do this?

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Here is what I have so far:

import java.io.File; import java.io.FilenameFilter; import java.util.ArrayList; import java.util.List; public class TestArrayList {     public static void main(String[] args) {         File f = new File(             "D:\\CBSE_Demo\\Demo_original\\fscommand\\contentplayer\\config");         List<String>temp=new ArrayList<String>();         temp.add(0, "N33");         temp.add(1, "N1417");         temp.add(2, "N331");         File[] matchingFiles = null;         for(final String temp1: temp){             matchingFiles = f.listFiles(new FilenameFilter() {                 public boolean accept(File dir, String name) {                     return name.startsWith(temp1);                 }             });             System.out.println("size>>--"+matchingFiles.length);          }     } } 

This does not copy the file, what is the best way to do this?

Answer 1

You can use this (or any variant):

Files.copy(src, dst, StandardCopyOption.REPLACE_EXISTING); 

Also, I'd recommend using File.separator or / instead of \\ to make it compliant across multiple OS, question/answer on this available here.

Since you're not sure how to temporarily store files, take a look at ArrayList:

List<File> files = new ArrayList(); files.add(foundFile); 

To move a List of files into a single directory:

List<File> files = ...; String path = "C:/destination/"; for(File file : files) {     Files.copy(file.toPath(),         (new File(path + file.getName())).toPath(),         StandardCopyOption.REPLACE_EXISTING); } 

Answer 2

Using Stream

private static void copyFileUsingStream(File source, File dest) throws IOException {     InputStream is = null;     OutputStream os = null;     try {         is = new FileInputStream(source);         os = new FileOutputStream(dest);         byte[] buffer = new byte[1024];         int length;         while ((length = is.read(buffer)) > 0) {             os.write(buffer, 0, length);         }     } finally {         is.close();         os.close();     } } 

Using Channel

private static void copyFileUsingChannel(File source, File dest) throws IOException {     FileChannel sourceChannel = null;     FileChannel destChannel = null;     try {         sourceChannel = new FileInputStream(source).getChannel();         destChannel = new FileOutputStream(dest).getChannel();         destChannel.transferFrom(sourceChannel, 0, sourceChannel.size());        }finally{            sourceChannel.close();            destChannel.close();        } } 

Using Apache Commons IO lib:

private static void copyFileUsingApacheCommonsIO(File source, File dest) throws IOException {     FileUtils.copyFile(source, dest); } 

Using Java SE 7 Files class:

private static void copyFileUsingJava7Files(File source, File dest) throws IOException {     Files.copy(source.toPath(), dest.toPath()); } 

Or try Googles Guava :

https://github.com/google/guava

docs: https://guava.dev/releases/snapshot-jre/api/docs/com/google/common/io/Files.html

Compare time:

    File source = new File("/Users/sidikov/tmp/source.avi");     File dest = new File("/Users/sidikov/tmp/dest.avi");       //copy file conventional way using Stream     long start = System.nanoTime();     copyFileUsingStream(source, dest);     System.out.println("Time taken by Stream Copy = "+(System.nanoTime()-start));           //copy files using java.nio FileChannel     source = new File("/Users/sidikov/tmp/sourceChannel.avi");     dest = new File("/Users/sidikov/tmp/destChannel.avi");     start = System.nanoTime();     copyFileUsingChannel(source, dest);     System.out.println("Time taken by Channel Copy = "+(System.nanoTime()-start));           //copy files using apache commons io     source = new File("/Users/sidikov/tmp/sourceApache.avi");     dest = new File("/Users/sidikov/tmp/destApache.avi");     start = System.nanoTime();     copyFileUsingApacheCommonsIO(source, dest);     System.out.println("Time taken by Apache Commons IO Copy = "+(System.nanoTime()-start));           //using Java 7 Files class     source = new File("/Users/sidikov/tmp/sourceJava7.avi");     dest = new File("/Users/sidikov/tmp/destJava7.avi");     start = System.nanoTime();     copyFileUsingJava7Files(source, dest);     System.out.println("Time taken by Java7 Files Copy = "+(System.nanoTime()-start));