methods | 易学教程

Could someone explain me the .getClass() method in java

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I am currently taking a java class in university. This is my first programming class and I've stumbled on something that I just cannot understand. As i learned, there are two ways of comparing variables. The first is using the == , != , < , > , =< , >= signs for PRIMITIVE variables such as int,double,etc. and the second way is to use the .equals() method for reference type. Now here is my question: When I use the .getClass() method, I can compare two classes with the .equals() method and the == / != method. Since I can use the == / != signs, I'd suppose that the .getClass() method which

After renaming a type, I cannot access some of its methods

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In order to prevent having multiple dependencies along different files of my project and since I might change how data will be presented, I decided to make an "interface" (not in the golang sense but in an architectural way) to the draw2d package As I didn't need anything else, I just renamed one of the types: type CanvasContext draw2dimg.GraphicContext In one of my modules I had the following code (path is a CanvasContext variable): // initialization and some code omitted for clarity path.SetFillColor(color.RGBA{0x44, 0xff, 0x44, 0xff}) path.SetStrokeColor(color.RGBA{0x44, 0x44, 0x44, 0xff})

Are programming languages and methods inefficient? (assembler and C knowledge needed)

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问题 for a long time, I am thinking and studying output of C language compiler in assembler form, as well as CPU architecture. I know this may be silly to you, but it seems to me that something is very ineffective. Please, don´t be angry if I am wrong, and there is some reason I do not see for all these principles. I will be very glad if you tell me why is it designed this way. I actually truly believe I am wrong, I know the genius minds of people which get PCs together knew a reason to do so.

Add method to metaclass

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问题 I'm just playing with the metaclass programming in Groovy. But suddenly I was facing a little problem which I just could not get working... Here is the simple script: // define simple closure def printValueClosure = { println "The value is: '$delegate'" } String.metaClass.printValueClosure = printValueClosure // works fine 'variable A'.printValueClosure() // define as method def printValueMethod(String s){ println "The value is: '$s'" } // how to do this!? String.metaClass.printValueMethod =

declare parameter subtype in Java interface, use subtypes in Java implementing methods

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I want to declare a method in an interface where the parameter of the method defined in implementing classes can be a subtype of a specific java class for example: interface Processor{ processRequest( Request r); } public class SpecialRequest extends Request{...} public class SpecialProcessor implements Processor{ processRequest(SpecialRequest r){...} } but I get errors in the SpecialProcessor because it doesn't properly implement the Processor interface. What can I change in the Processor interface to allow the definition in the SpecialProcessor to work? You can type Processor : public

What's the rationale/history for the # convention of identifying methods in Ruby?

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问题 For example, I've always seen methods referred to as String#split , but never String.split , which seems slightly more logical. Or maybe even String::split , because you could consider #split to be in the namespace of String . I've even seen the method alone, when the class is assumed/implied ( #split ). I understand that this is the way methods are identified in ri. Which came first? Is this to differentiate, for example, methods from fields? I've also heard that this helps differentiates

How do I sum up records within Rails 3?

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I have an ItemsSold model which has the total number of magazines, books, videos, greeting_cards, pens sold for a single day. How do I elegantly return an array with the weekly sold totals for each item for the last arbitrary number of weeks? I have a model file: #items_sold.rb class ItemsSold < ActiveRecord::Base attr_accessible :magazines, :books, :videos, :greeting_cards, :pens, :sold_date end My table is defined as follows: t.integer :magazines t.integer :books t.integer :videos t.integer :greeting_cards t.integer :pens t.datetime :sold_date Also, is it possible to return monthly totals

Ruby on Rails 3: How to retrieve POST and GET params separately?

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问题 I know you can get parameters using params , but the thing is that it merges all parameters whether they were sent via GET or POST : If you send a request via GET , no problem, the parameters can only be squeezed in the URL. But if you send a POST request that has a URL like /blabla?foo=bar&foo2=bar2 , is there a way to tell the difference between the variables sent via the URL and the variables sent through the actual POST method? 回答1: Yes, in your controller you can get the GET parameters

Find first N pentagonal numbers

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I have to find the first N [pentagonal numbers][1] from 1-100 and display them 10 per line. I have to use the getPentagonalNumber(int n) method as well; that is obviously why it is there. Here is my code so far. package chapter_5; public class Five_One { public static void main(String[] args) { int n = 0; int numPerLine = 10; for ( n = 0; n < 11; n ++) } public static int getPentagonalNumber(int n) { int formula = n * (3 * n - 1) / 2; while ( formula < ) } } This has a long way to go. Let's break it down here with a better approach. Let's make a method that returns a set number of pentagonal

Overriding jQuery plugin methods, as default and for single instances

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The basic question is: How do I perform a basic override of a plugin method without editing the original plugin file? Is it possible to create an override for a specific instance: Example: An rtf plugin uses: $('selector').wysiwyg('setContent',newContent); In order to display the rtf text as readonly I would like for the same method to be applied to a div instead of the body of the IFRAME I would like to overwrite the original 'setContent' with my own code, just for this one element. Thanks jAndy (function($){ var _oldcss = $.fn.css; $.fn.css = function(prop,value){ if (value.toLowerCase() ===