methods

问题 What is the purpose of a constructor? I've been learning Java in school and it seems to me like a constructor is largely redundant in things we've done thus far. It remains to be seen if a purpose comes about, but so far it seems meaningless to me. For example, what is the difference between the following two snippets of code? public class Program { public constructor () { function(); } private void function () { //do stuff } public static void main(String[] args) { constructor a = new

问题 I'm doing Code Academy's tutorials on Python, and I'm a bit confused about the definition of method and function. From the tutorial: You already know about some of the built-in functions we've used on (or to create) strings, such as .upper() , .lower() , str() , and len() . Coming from C++, I would think .upper() and .lower() would be called methods and len() and str() functions. In the tutorial, the terms seem to be used interchangeably. Does Python distinguish between methods and functions

问题 This question already has answers here : Why use getters and setters/accessors? (38 answers) Closed 3 years ago . I have been taught to always use getters and setters. However, I don't know the pros and cons of these methods, as by implementing them we are exposing the data and also hiding it. I am a little confused about this. Can anybody give some proper advice on why we use a getter/setter and what the advantages are? 回答1: The basic "private field with public getter and setter that do

问题 I seem to remember that in PHP there is a way to pass an array as a list of arguments for a function, dereferencing the array into the standard func($arg1, $arg2) manner. But now I'm lost on how to do it. I recall the manner of passing by reference, how to "glob" incoming parameters ... but not how to de-list the array into a list of arguments. It may be as simple as func(&$myArgs) , but I'm pretty sure that isn't it. But, sadly, the php.net manual hasn't divulged anything so far. Not that I

问题 Let's say I have a class designed to be instantiated. I have several private "helper" methods inside the class that do not require access to any of the class members, and operate solely on their arguments, returning a result. public class Example { private Something member; public double compute() { double total = 0; total += computeOne(member); total += computeMore(member); return total; } private double computeOne(Something arg) { ... } private double computeMore(Something arg) {... } } Is

问题 This seems to occur a lot, and was wondering if this was a requirement in the Python language, or merely a matter of convention? Also, could someone name and explain which functions tend to have the underscores, and why ( __init__ , for instance)? 回答1: From the Python PEP 8 -- Style Guide for Python Code: Descriptive: Naming Styles The following special forms using leading or trailing underscores are recognized (these can generally be combined with any case convention): _single_leading

问题 I want to know how to list all methods available for an object like for example: alert(show_all_methods(Math)); This should print: abs, acos, asin, atan, atan2, ceil, cos, exp, floor, log, max, min, pow, random,round, sin, sqrt, tan, … 回答1: You can use Object.getOwnPropertyNames() to get all properties that belong to an object, whether enumerable or not. For example: console.log(Object.getOwnPropertyNames(Math)); //-> ["E", "LN10", "LN2", "LOG2E", "LOG10E", "PI", ...etc ] You can then use

问题 In my Orange class I have this method: public static List<Orange> AddOrange() { List<Orange> oranges = new List<Orange>(); oranges.Add(new Orange() { Weight = 150, Measure = 6 }); oranges.Add(new Orange() { Weight = 160, Measure = 6 }); oranges.Add(new Orange() { Weight = 160, Measure = 6 }); oranges.Add(new Orange() { Weight = 150, Measure = 6 }); oranges.Add(new Orange() { Weight = 160, Measure = 6 }); oranges.Add(new Orange() { Weight = 160, Measure = 6 }); return oranges; } And in my

问题 I want click method to be called only once, what can I do get this result? here's my code: public override View GetView(int position, View convertView, ViewGroup parent) { View result = convertView; if (result == null) { result = LayoutInflater.From(_Context).Inflate(Resource.Layout.DiagnoseTemplateLayout, null, false); } TextView textView = result.FindViewById<TextView>(Resource.Id.DiagnoseTemplateTextView); textView.Text = _Diagnoses[position].Description; Button button = result

问题 I am refactoring an extensive codebase overtime. In the long run we are going to develop the whole system in classes but in the mean time I am using the opportunity to refine my PHP skills and improve some of the legacy code we use across several hundred websites. I have read conflicting articles over time about how best to return data from a custom function, generally the debate falls into two categories, those concerned about best technical practice and those concerned about ease of reading