File renameTo()

[Kedar Nath]

I was trying with file operation.

import java.io.*;

class file{
    public static void main(String arg[]){ 
        try
        {
            File dir1= new File("pack1");
            dir1.mkdir();

            File f1= new File(dir1 ,"niky.txt");
            f1.createNewFile();
            
            File dir2= new File("pack2");
            dir2.mkdir();
            
            File f2= new File(dir2,"rex.txt");
          
            
            
            System.out.println( f1.isFile() ); 
	    System.out.println( f2.isFile() ); 

            System.out.println(f1.getName());
            System.out.println(f2.getName());

	    System.out.println(f1.getPath());
	    System.out.println(f2.getPath());

	    System.out.println();
            System.out.println( f1.renameTo(f2) );
      	    System.out.println(); 

            System.out.println( f1.isFile() ); 
	    System.out.println( f2.isFile() );

	    System.out.println(f1.getName());
            System.out.println(f2.getName());

	    System.out.println(f1.getPath());              
            System.out.println(f2.getPath()); 
            
        
        }
        catch (IOException e){
            System.out.println("Got punked");
        }
        
    }
}

OUTPUT is

true
false
niky.txt
rex.txt
pack1\niky.txt
pack2\rex.txt

true

false
true
niky.txt
rex.txt
pack1\niky.txt
pack2\rex.txt

Why is the path and name of the file still the SAME ??

[Punit Singh]

   System.out.println( f1.renameTo(f2) );    

It has done its work, just try to find pack1\niky.txt on your file system.

[Maneesh Godbole]

Please use meaningful titles.
Having a thread titled "File" hardly makes sense.

[Kedar Nath]

No , i find only find pack2\rex. And nothing in pack1

[Hemnathbabu Kottaiveedu]

Hi Kedar,

The code

   System.out.println( f1.renameTo(f2) ); 

renames the file referenced by variable f1 to the abstract file name of f2. The abstract path names of f1 and f2 are:

f1: pack1\niky.txt
f2: pack2\rex.txt

So after the above code is executed you will observe that the file name of f1 is changed to pack2\rex.txt and therefore you will find rex.txt file created under pack2 dir. So after the code is executed f1 is pointing to a file object which is still not created and f2 is pointing to an actual file on disk.

Hope this clears your doubt.

Thank You
Hemnath

[Kedar Nath]

Unfortunately , i did not understand. Can you explain that again??

[Punit Singh]

Kedar Nath wrote:Unfortunately , i did not understand. Can you explain that again??

Just remember whatever pointed by f1 on filesystem that is pack1\nicky.txt, is renamed to pack2\rex.txt, and nicky.txt got deleted.

But f1 is just pointing to pack1\nicky.txt, but if you call f1.exists() you will get false, as whatever pointed by f1 on filesystem is deleted.
and f2.isFile() will return true as f1.renameTo(f2) has created pack2\rex.txt that is pointed by f2.

f1 and f2 just a reference of the File object, File Object is just like any java object, the actual file on file system will be created when you call File.createNewFile() method.

File Object has a instance variable that is String path, this path variable just stores address of the files like pack1\nicky.txt, but this pack1\nicky.txt could or could not exist on the file system. You can check that via calling exists() method.

[Hemnathbabu Kottaiveedu]

Yes why not.

When you execute the renameTo method on the file object the original file(f1 with abs path pack1\niky.txt) is renamed with the abs path of f2(pack2\rex.txt). So the file location is changed and you will find the file created in pack2 directiory.

And the system out statements that you have put at the end of the program clearly shows that f1 is no more a file now and f2 is actually pointing to a file with name rex.txt.

Thanks,
Hemnath

[Kedar Nath]

Thankyou guys , Now i understood.