Java Programming

i wonder what is diffrent between 2 options.

case 1.
import java.util.*;

case 2.
import java.util.AbstractCollection;
import java.util.AbstractList;
import java.util.ArrayList;
import java.util.BitSet;
import java.util.Calendar;
import java.util.Date;


if i declare import sentece like case 1.
all classes in java.util. are imported when compiling ?
so can it be little longer than case 2 ?

i wonder, if i declare import like case1, is it bad things for performance ?