No implicit methods. You must notify the instance when that happens. See this example: class Beer{ private $ingredients = []; public function addIngredient(Ingredient $ing){ $this->ingredients[] = $ing; $ing->setOwner($this); } } class Ingredient{ private $owner; public function getOwner(){ return $this->owner; } public function setOwner($owner){ $this->owner = $owner; } public function hasOwner() : bool{ return isset($this->owner); } … Read more
Comparable is an interface already implemented in Java. https://docs.oracle.com/javase/8/docs/api/java/lang/Comparable.html http://tutorials.jenkov.com/java/interfaces.html What you need to do there is create two classes Customer (which implements Comparable) and HighEarner which inherits Customer. You also need a main class which you can name whatever(ex: Program or FlowerShop). solved Understanding the requirement of an OOP programming [closed]
Interfaces are public “contracts” whenever you want to be able to swap the implementation or give someone the flexibility to use another implementation you should use interfaces. Example: You want to store something so you can load it later. You could use something like public function save(MySQL $db, array $data); But this is not very … Read more
Under the C++11 standard, we can supply an in-class initializer for a data member. When we create objects, the in-class initializers will be used to initialize the data members. Members without an initializer are default initialized. Your first example uses an in-class initializer, while your second example only initializes a within the default constructor. Say … Read more
Java does not allow you to use super as a value. You cannot return it. And you don’t need to return it, because you can reference the object with this. In Java, an instance of class is represented by one object. The superclass is not represented by a separate object. Classes support inheritance of implementation … Read more
Nothing. When using the object initialiser syntax { }, the () for a parameterless constructor is optional. From the overview of C# 3.0, where this syntax was introduced: An object creation expression can omit the constructor argument list and enclosing parentheses, provided it includes an object or collection initializer. Omitting the constructor argument list and … Read more
That’s a very good question. It goes down to the dark heart of the plugin API and best programming practices. For the following answer I created a simple plugin to illustrate the problem with easy to read code. <?php # -*- coding: utf-8 -*- /* Plugin Name: Anonymous OOP Action */ if ( ! class_exists( … Read more
Expression 1 – int a; int* ap = &a; Ans : This is an int pointer which will stay on the stack. Expression 2 – int a; int*ap = new a; **// syntax error** Ans: new will allocate memory in heap and this needs manual cleanup (using delete), whereas in Expression 1 it will automatically … Read more
Main m = new Main(); This code in class B will simply create an object of Main class. After this you need to call this to fill the arrayList. m.add() 1 solved Java Inheritance not working
Any of the following solutions will work: Remove the keyword, public from the definition of the classes, Circle and Square Write the classes, Circle and Square as they are (i.e. with public keyword) in separate files. The reason is that Java supports only one public class in a source file. A couple of more points: … Read more
Java is designed to be fully object-oriented while C is a procedural language. I suggest looking at http://www.tutorialspoint.com/cprogramming/c_overview.htm to read about C. Java is not meant to be used for procedural. This is all I can do to help. You need to do some research on the programming paradigms. Practical Explanation : Can anyone Explain … Read more
You can do this with whatever class you want, but here’s a quick example using namedtuple >>> from collections import namedtuple >>> Point = namedtuple(‘Point’, ‘x y’) >>> def my_func(): return Point(1, 9) >>> my_func().x 1 This code is completely useless though 8 solved function returning an object in python [closed]
It is called chainable methods. In order to apply a method on $theclassvariable it needs to be an instance of a class. Let’s define it: class myClass { public function __construct() { echo ‘a new instance has been created!<br />’; } public function firstMethod() { echo ‘hey there that\’s the first method!<br />’; return $this; … Read more
You never assign an initial node. This is the kind of problem that a sheet of paper, a pencil, and two minutes of drawing arrows and boxes should solve, and until you’re fluent in dynamic allocation get used to doing a lot of that. This: if(start==NULL) { p->next=NULL; p->prev=NULL; // NOTE: start is still NULL … Read more
Simply pass the object of the created ArrayList to the function as paramter. Here’s a short example for printing the ArrayList: Assuming you put the code inside a class, leaving a snippet here. I’ll demonstrate it with Integer examples. static void printArrayList(ArrayList<Integer> a){ for(Integer i:a) System.out.print(i+” “); System.out.println(“”); } //in the main function: public static … Read more