How to copy a file in Java

Even the most basic of task – like copying a file – can be done in several different ways in Java…
a testament to the richness of the platform (or its complexity !).

Four possible ways to copy a file below, all error handling left aside.

1- the complicated way, manipulating io streams.

   import java.io.FileInputStream;
   import java.io.FileOutputStream;
   import java.io.InputStream;
   import java.io.OutputStream;
   ....

   String orig ="file.xml";
   String dest = "file.xml.bak";
   InputStream in = new FileInputStream(orig);
   OutputStream out = new FileOutputStream(dest);
   byte[] buf = new byte[1024];
   int len;
   while ((len = in.read(buf)) > 0) {
      out.write(buf, 0, len);
   }
   in.close();
   out.close(); 

2- The ugly , non-portable way, using the operating system environment:

   Runtime.getRuntime().exec("OS dependent file copy command here"); 

3- The opensource way, using the Apache Commons library.

   import java.file.io;
   import org.apache.commons.io.FileUtils;
   ....
   String orig ="file.xml";
   String dest = "file.xml.bak";
   File fOrig = new File(orig);
   File fDest = new File(dest);
   FileUtils.copyFile(fOrig, fDest);

4- The novel way- using Java 7 and it’s revamped I/O api.

   
    import java.io.File;
    import java.nio.file.Path;
    ...
    String orig ="file.xml";
    String dest = "file.xml.bak";
    File f = new File (orig);
    Path p = f.toPath();
    p.copyTo(new File (dest).toPath(), REPLACE_EXISTING, COPY_ATTRIBUTES);

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