I had the very same issue, not being able to instantiate the type of a class which I was absolutely sure was not abstract. Turns out I was implementing an abstract class from Java.util
instead of implementing my own class.
So if the previous answers did not help you, please check that you import
the class you actually wanted to import, and not something else with the same name that you IDE might have hinted you.
For example, if you were trying to instantiate the class Queue from the package myCollections which you coded yourself :
import java.util.*; // replace this line
import myCollections.Queue; // by this line
Queue<Edge> theQueue = new Queue<Edge>();