Actually i figured out a very small mistake by accident
Thanks to both of your help for the assistance
Note for other people references : In fact, my code was working perfectly fine. If I compile and run in through cmd it works perfectly fine and read the file i wanted to open.
Since i tried to run it using IDE (Eclipse) which create some default directory and few supporting files. It mislead the targeting directory that i want.(by adding another folder with the name "src")
So in general for other people who face the same problem like I did, my tips will be, check your original directory by printing the current directory