在事先不知道软件包的情况下加载Java类

Question

I have been using the below code to load the classes where I knew the package to load.

ClassLoader classLoader = ClassLoader.getSystemClassLoader();

Class<?> myClass = classLoader.loadClass(classNameToBeLoaded);

There is now change in the folder/package structure.

The variable classNameToBeLoaded can be from any package which I can't know in advance as the class name comes from an user provided Excel sheet.

For example the value of classNameToBeLoaded can be "Utils", "FileValidation" etc as read from Excel file.

This class can be from different packages like "com.iyaffle.utils" or like "com.testing.validation" or anything so.

How can I make the class to be loaded automatically when we don't know the package name?

Other similar thread which does not have concrete answers:

• Load all classes in a specific folder without knowing package name - java

Answer 1

You do need to know the fully qualified name to load the classes, there are lots of classes that have the same class name, and the only thing that keeps them distinct is the package name.

A good example is the following:

• java.awt.List
• java.util.List

If the classes do not have common methods you need to call you can just load them like you are doing now, but adding on the package name.

The safest way to call common methods is to have a static interface or abstract class that all your dynamic classes extend, so that you can then treat the dynamically loaded class instances as instances that implement the common methods.