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  Java Polymorphism and Overriding Methods

Most Java developers will be familiar with polymorphism – we’ve all seen the example of the Dog and Cat classes inheriting from some abstract Animal class and having their say() methods produce different results. But it’s still worthwhile to look at a few simple examples to reinforce the concepts.First, we define a simple class with one instance method and one static method.public class A { public String getName() { return "I a...

   Java,Overriding,Polymorphism,Demo,Dynami     2011-10-04 14:09:06

  What does super.clone() do?

Object class has a protected clone() method declared to make it possible for all classes make a clone of itself when needed. The clone() is often used when a new instance of the class is needed while at the same time to maintain the same state as the original object. Any class which wants to have clone enabled has to implement the marker interface Cloneable. If a class which implements Cloneable doesn't override the Object.clone() method, the Object.clone() method will be called to just make a b...

   Cloneable,super.clone(),clone,Java     2015-01-07 05:25:52

  Can private method be overridden?

The private methods are not inherited by subclasses and you cannot be overridden by subclasses. According to Java Language Specification (8.4.8.3 Requirements in Overriding and Hiding), "Note that a private method cannot be hidden or overridden in the technical sense of those terms. This means that a subclass can declare a method with the same signature as a private method in one of its superclasses, and there is no requirement that the return type or throws&nb...

   Java,Private method,overridding,impossib     2011-10-06 03:57:14

  Polymorphism in OOP programming

Polymorphism is the capability of an action or method to do different things based on the object that it is acting upon. This is the third basic principle of object oriented programming. Overloading, overriding and dynamic method binding are three types of polymorphism. Overloaded methods are methods with the same name signature but either a different number of parameters or different types in the parameter list. For example 'spinning' a num...

   Java,OOP,Polymorphism,Overloading,Overri     2014-10-23 08:11:50

  A String is not an Error

I decided to write a little article to discourage an unfortunately common pattern in Node.JS modules (and browser JavaScript, to a lesser extent) that can boil down to these two examples: // A:function myFunction () {  if (somethingWrong) {    throw 'This is my error'  }  return allGood;} and // B: async Node.JS-style callback with signature `fn(err, …)`function myFunction (callback) {  doSomethingAsync(function () {    // …    if (...

   JavaScript,Node.js,String,Error object     2011-12-23 08:00:32

  Why learning Haskell/Python makes you a worse programmer

I've found, contrary to what you sometimes read, that learning Python and Haskell has not improved my programming using other languages. Haskell in particular, being so different from imperative languages, is supposed to give new insights into programming that will help you even when you are not using the language. My current experience doesn't exactly tally with this, and here is why:Demotivation.I find I think in Python, and even in Haskell to some extent, even though I have used Has...

   Python,Programmer,Bad,Bad programmer,Haskell     2011-10-29 07:13:44

  File System vs Core Data: the image cache test

Code for this project is on GitHub While doing a full re-write of Droplr's iOS app for the 2.0 launch, I couldn't find any good file/image caches out there had a particular feature I really wanted: extending item expiration whenever it's touched. I set out to write my own — which wasn't that much of a challenge — but somewhere along the process I had this crazy idea that perhaps (SQLite-backed) Core Data would be a much better tool for the job: No mismatch between cache index ...

   File system.Image cache,Multimedia     2012-02-01 08:52:02

  Use cases of Java enumeration

JDK 1.5 introduces a new type -- enumeration. In Java, it's just a small feature, but it can bring us much convenience.Here we summarize some use cases of Java enumeration. 1. Constant Prior to JDK 1.5, we can define constant as public static final..., now we can use enumeration to group all constants in one enum variable and it also provides some useful functions. public enum Color {     RED, GREEN, BLANK, YELLOW   }  2.In Swit...

   Java, Enum,enumeration     2013-01-05 09:15:30

  Vim: revisited

I’ve had an off/on relationship with Vim for the past many years. Before, I never felt like we understood each other properly. Vim is almost useless without plugins and some essential settings in .vimrc, but fiddling with all the knobs and installing all the plugins that I thought I needed was a process that in the end stretched out from few hours to weeks, months even; and it the end it just caused frustration instead of making me a happier coder. Recently, I decided to give Vim ano...

   Linux,Editor,Vim,Setup,Quick guideline     2011-12-12 07:55:27