为什么在以下代码中执行后，Java Priority Queue不为空？

I am trying to implement Dijkstra Algorithm and have used the following code. I have used the debugger in Eclipse to step through the program and have found that it produces correct values mid way through the execution. However after that, the priority queue that I have used from the java.util package, does not show up to be empty. While theoretically it should be empty from the following code.I am trying to implement Dijkstra Algorithm and