java - Finding a class reflectively by its simple-name alone

Question

I was wondering if there is any given function that allows me to introspect a class without having to write the packages where the class is contained.

For example, I want to take a look at the methods and superclasses of the class Integer in order to do that I have to specify the packages where the class is located. This will be "java.lang.Integer"

Instead of doing that I want to just type the class name in order to have the information of the class displayed. Just like this "Integer"

How can I make that my program just check the class name, no matter where is it located?

Answer 1

Java will not stop you from creating your own my.company.Integer class and my.other.company.Integer class, so how it cannot know which Integer class is the right one.

The closes thing to an answer I can suggest is to create a pre-defined list of packages where you want to search the class for, and keep trying each until you find your class.

So something like:

class ClassFinder{
  public static final String[] searchPackages = {
    "java.lang",
    "java.util",
    "my.company",
    "my.company.other" };

  public Class<?> findClassByName(String name) {
    for(int i=0; i<searchPackages.length; i++){
      try{
        return Class.forName(searchPackages[i] + "." + name);
      } catch (ClassNotFoundException e){
        //not in this package, try another
      } catch (...){
        //deal with other problems...
      }
    }
    //nothing found: return null or throw ClassNotFoundException
    return null;
  }
}

If you want to get a list of all available packages instead of hard-coding them, see here.

Be warned that this method is unlikely to perform very well, so use it sparingly.