Upsides and downsides of importing specifically and importing overally

Question

I noticed that people prefer importing javax.swing.JFrame instead of javax.swing.* , importing java.math.BigInteger instead of java.math.* , etc... Is there any downside of importing the whole package instead of importing specifically or is there any upsides importing specifically?

Answer 1

Well one point I've have read against package imports is that they cause problems if the classes are added to the package later causing ambiguity . Like jdk 1.1 contained just one List class in java.awt package , jdk1.2 introduced another List class in java.util package .

Answer 2

Usually single class imports are preferred because they make it easy to figure which class is imported. And with modern IDE it's very easy. So it's often considered a good style. There is no difference between package and single class imports.