Copy a file to other destination and show the modification time of destination file

This is detailed java code that copies a source file to destination file, this code checks all the condition before copy to destination file, for example- source file is exist or not, source file is readable or not etc.
In the example code given below we have used command line argument as file name, first argument will be path of the source file and second will be the path of destination file. If we provide only file names instead of full path, code will try to search source file in the same directory where java code file has been saved. If destination file is not found in given directory this will create a new file and write content of source file in same, if destination file is already exist code will ask weather you want to overwrite file or not.


CopyFile.java

import java.io.*;
import java.util.*;

public class CopyFile {

    public static void copy(String source, String 
    destination) throws IOException {
        File source_file = new File(source);
        File desti_file = new File(destination);
        FileInputStream fis = null;
        FileOutputStream fos = null;
        byte[] buffer;
        int byte_read;

        try {

            /* first check that file exists or not. */
            if (!source_file.exists() || !source_file.isFile()) 
            {
                throw new ClassException("No source file 
                found : "+source);
            }

        /* check that the file is readable or not. */
            if (!source_file.canRead()) {
                throw new ClassException("Source file is 
                unreadable: "+source);
            }

            /* If the destination exists, make sure it is a 
            writeable file and ask before overwriting it. 
            If the destination doesn't exist, make sure the 
            directory exists and is writeable.*/
            if (desti_file.exists()) {
                if (desti_file.isFile()) {
                    DataInputStream in = 
                    new DataInputStream(System.in);

                    if (!desti_file.canWrite()) {
                        throw new ClassException("Destination 
                        is unwriteable : "+destination);
                    }
                    System.out.print("File " + destination + 
                    " already exists. Overwrite?(Y/N): ");
                    System.out.flush();
                    String response = in.readLine();
                    if (!response.equals("Y") && 
                         !response.equals("y")) {
                        throw new ClassException("Wrong 
                        Input.");
                    }
                } 
        else {
                   throw new ClassException("Destination is 
                   not a normal file: " + destination);
                }
            } 
        else {
                File parentdir = parent(desti_file);
                if (!parentdir.exists()) {
                    throw new ClassException("No Destination 
                    directory exist: " + destination);
                }
                if (!parentdir.canWrite()) {
                    throw new ClassException("Destination 
                    directory is unwriteable: " 
                            + destination);
                }
            }

            /* Now we have checked all the things so we can 
            copy the file now.*/
            fis = new FileInputStream(source_file);
            fos = new FileOutputStream(desti_file);
            buffer = new byte[1024];
            while (true) {
                byte_read = fis.read(buffer);
                if (byte_read == -1) {
                    break;
                }
                fos.write(buffer, 0, byte_read);
            }
        } 

        /* Finally close the stream. */ 
    finally {
              fis.close();
          fos.close();              
        }

        // Access last modification date of destination file.
        System.out.print("Last modification date of 
        destination file : ");
        System.out.println(new Date(desti_file.lastModified()));
    }

    /* File.getParent() can return null when the file is 
    specified without a directory or
    is in the root directory. This method handles those cases.*/
    private static File parent(File f) {
        String dirname = f.getParent();
        if (dirname == null) {
            if (f.isAbsolute()) {
                return new File(File.separator);
            } 
        else {
                return new File(System.getProperty("user.dir"));
            }
        }
        return new File(dirname);
    }

    public static void main(String[] args) {
        if (args.length != 2) {
            System.err.println("Wrong argument entered. 
            Try Again......");
        } 
    else {
            try {
                copy(args[0], args[1]);
            } 
        catch (IOException ex) {
                System.err.println(ex.getMessage());
            }
        }
    }
}

class ClassException extends IOException {

    public ClassException(String msg) {
        super(msg);
    }
}

Output of the program :

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