Why is using a wild card with a Java import statement bad?

Question

It is much more convenient and cleaner to use a single statement like

import java.awt.*;

than to import a bunch of individual classes

Answer 1

Here are the few things that I found regarding this topic.

• During compilation, the compiler tries to find classes that are used in the code from the .* import and the corresponding byte code will be generated by selecting the used classes from .* import. So the byte code of using .* import or .class names import will be same and the runtime performance will also be the same because of the same byte code.

• In each compilation, the compiler has to scan all the classes of .* package to match the classes that are actually used in the code. So, code with .* import takes more time during the compilation process as compared to using .class name imports.

• Using .* import helps to make code more cleaner

• Using .* import can create ambiguity when we use two classes of the same name from two different packages. Eg, Date is available in both packages.

    import java.util.*;
    import java.sql.*;
  
    public class DateDemo {
        private Date utilDate;
        private Date sqlDate;
    }