instance-variables

background I have an android project that uses JNI (using NDK) to code in both Java and C/C++. I've created a Jni java wrapper on the java side that will do all the Jni oprerations by itself, while no other java class can access the jni operations directly other than this wrapper. the problem problem is , i wish to create multiple instances of this wrapper, while the Jni part should have an instance per Jni wrapper. this is a problem, since the Jni part holds the same fields for all instances. the question How can i solve this problem, so that for each java instance of the jni wrapper, there

I have a class that essentially acts as a light weight wrapper class around another class. It holds that other class as an iVar. I want to be able to expose certain properties (quite a few actually) of the iVar, but to do so I have to write out each property accessor like so: - (void) setProperty:(Class *)value{ _iVar.property = value; } - (Class *) property{ return _iVar.property; } Of course, I have to do this for every single property, which is a pain (there are about 30 of them). I would love to be able to synthesize this but I haven't been able to figure out how. Is it possible to

I've been running into this problem many times and I never bothered to learn why its happening and learn what "static" actually means. I just applied the change that Eclipse suggested and moved on. public class Member { // Global Variables int iNumVertices; int iNumEdges; public static void main(String[] args) { // do stuff iNumVertices = 0; // Cannot make a static reference to the non-static field iNumVertices // do more stuff } // main end } So eclipse tells me to do static int iNumVertices; and I'm not sure why. So what exactly is "static", how is it used, what is the purpose of using

What's the difference between declaring a @private ivar in the header file and declaring the same ivar in the class extension without @private? As far as I understand it's the same thing. Also, can you declare a private property in the header? What's the difference between declaring a @private ivar in the header file and declaring the same ivar in the class extension without @private? There are a few differences. In short, variables declared in the header file are visible to subclasses and class categories. Variables declared in the implementation are not. 1) Instance variables declared in a

I am having a hard time understanding instance variable, class variable and the difference between them in ruby... can someone explain them to me? I have done tons of Google searches, just can't understand them fully. Thank you! Let's say you define a class. A class can have zero or more instances. class Post end p1 = Post.new p2 = Post.new Instance variables are scoped within a specific instance. It means if you have an instance variable title , each post will have its own title. class Post def initialize(title) @title = title end def title @title end end p1 = Post.new("First post") p2 = Post

I'm thinking in: class X def new() @a = 1 end def m( other ) @a == other.@a end end x = X.new() y = X.new() x.m( y ) But it doesn't works. The error message is: syntax error, unexpected tIVAR How can I compare two private attributes from the same class then? There are several methods Getter: class X attr_reader :a def m( other ) a == other.a end end instance_eval : class X def m( other ) @a == other.instance_eval { @a } end end instance_variable_get : class X def m( other ) @a == other.instance_variable_get :@a end end I don't think ruby has a concept of "friend" or "protected" access, and

My questions concern instance variables that are initialized in methods outside the class constructor . This is for Python. I'll first state what I understand: Classes may define a constructor, and it may also define other methods. Instance variables are generally defined/initialized within the constructor. But instance variables can also be defined/initialized outside the constructor, e.g. in the other methods of the same class. An example of (2) and (3) -- see self.meow and self.roar in the Cat class below: class Cat(): def __init__(self): self.meow = "Meow!" def meow_bigger(self): self.roar