如何在Eclipse内的JAR文件中引用类和方法？

Question

Basically I wish to use the methods of a class within the Jar file, which looks like this:

Can somebody please tell me what I need to import in order to use those methods and variables?

Answer 1

You don't need to import anything.

Jar files aren't imported , they are added to the classpath.
From the screenshot you've posted, we can see that the myJar.jar file is included in your eclipse classpath, so there's nothing more to do there.

Classes are imported, if they are in a different package.
Your Examplew class is in the default package . BMIcalculator is also in the default package . Because they are the same package, you don't need to import it.

You should be able to simply make references to BMIcalculator from within Examplew . Just try it.

Try compiling this code - it should work:

public class Examplew
{
    private BMIcalculator calc = new BMIcalculator();
}

You might get warnings about the unused private field, but you can ignore that for now.

If that doesn't work for you, then please post the error, because it doesn't look like the problem is with your imports (or your classpath)

Answer 2

Quote from this question :

You can't use classes in the default package from a named package.

Prior to J2SE 1.4 you could import classes from the default package using a syntax like this:

import Unfinished;

That's no longer allowed . So to access a default package class from within a packaged class requires moving the default package class into a package of its own.

If you have access to the source generated by groovy, some post-processing is needed to move the file into a dedicated package and add this "package" directive at its beginning.