learning-java | Java编程之路

What does it mean by "Casting affects the selection of overloaded methods at compile time but not overridden methods"?

I read the following passage on "Overridden methods and dynamic binding" (https://www.oreilly.com/library/view/learning-java-4th/9781449372477/ch06s01.html) and I couldn't understand the last paragraph

"In a previous section, we mentioned that overloaded methods are selected by the compiler at compile time. Overridden methods, on the other hand, are selected dynamically at runtime. Even if we create an instance of a subclass our code has never seen before (perhaps a new class loaded over the network), any overriding methods that it contains are located and used at runtime, replacing those that existed when we last compiled our code.

In contrast, if we created a new class that implements an additional, more specific, overloaded method, and replace the compiled class in our classpath with it, our code would continue to use the implementation it discovered originally. This situation would persist until we recompiled our code along with the new class. Another effect of this is that casting (i.e., explicitly telling the compiler to treat an object as one of its assignable types) affects the selection of overloaded methods at compile time but not overridden methods."

I couldnt understand the "Casting" line: "Another effect of this is that casting (i.e., explicitly telling the compiler to treat an object as one of its assignable types) affects the selection of overloaded methods at compile time but not overridden methods."

I am trying to use Mike Bostock's 'Observable' to re-create a simple HTML webpage, but I am encountering TypeError: Cannot read property 'timeFormat' of undefined in reference to the line of code that draws the chart, namely:

d3.select('#events').data([repositoriesData]).call(chart);

As visible in my notebook, the error points to the .call(chart) parameter.

Can anyone help me why I get this error in Observable when the script works just fine in HTML? And how can I fix it?

As evinced by Alpesh Jikadra comment and jsFiddle (below), the JavaScript function works just fine when embedded in a standard HTML page:

I created a sample struts 2 project & J-unit test case by referring the link.

Below is my POM file.

I am a member of Safaribooksonline.com and I love it.

Now I would like to save a list of the books that I have in my library.

If I look at the html-source of the books list, I have divs like [1] below within the class "main".

I loaded jQuery into the browser console and then selected all "main" divs with books_list = jQuery(".main"). This gives me an Object with entries like Object { 0: , 1: ....

I can iterate over these entries and extract the sub-infos (book title etc).

What is the most idiomatic way to get the sub-divs and sub-infos from these main divs? Ideally in JSON format. So that I have {title: "book title", author: "book author", etc}

[1] Divs containing book infos

I created a sample struts 2 project & junit test case by referring the below link.

http://self-learning-java-tutorial.blogspot.com.au/2015/04/struts2-junit-integration.html

But, while executing the test case I am getting following error,

Error in Eclipse JUNIT stacktrace

Can Anyone advice me how to resolve this issue ?