Many of us have this question regarding importing classes:

If we need to use some classes from a package, and we import whole package , will it make performance of our class slow?

Actually it has no affect on the performance. Its a good programming practice to import only the classes that you need.

Importing only the classes I need:
Java Code:
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
...

Importing the whole package:
Java Code:
import java.io.*;
...