As a formal method parameter is a local variable, you can access them from inner anonymous classes only if they are declared as final. This saves you from declaring another local final variable in the method body: void m(final int param) { new Thread(new Runnable() { public void run() { System.err.println(param); } }).start(); }
It’s three completely different things: public means that the method is visible and can be called from other objects of other types. Other alternatives are private, protected, package and package-private. See here for more details. static means that the method is associated with the class, not a specific instance (object) of that class. This means … Read more
In fact your code will not compile – int c = int a is not valid. I assume that you meant: – int c = a;. How can i then use variable c and d in a method within the same class as the constructor You can’t because you have declared them as local variables … Read more
Pointers are values just like let’s say int numbers. The difference is the interpretation of that value: pointers are interpreted as memory addresses, and ints are interpreted as integer numbers. When you want to change the value of a variable of type int, you pass a pointer to that int which is of type *int, … Read more
Your code fails as it cannot pickle the instance method (self.cal), which is what Python attempts to do when you’re spawning multiple processes by mapping them to multiprocessing.Pool (well, there is a way to do it, but it’s way too convoluted and not extremely useful anyway) – since there is no shared memory access it … Read more
In terms of the actual error here, if parseYouTubeAndYahoo class is a non-static inner class inside of your Activity, then you need an instance of the enclosing class in order to instantiate the inner class. So, you’ll need: MainActivity myActivity = new MainActivity(); MainActivity.parseYouTubeAndYahoo asyncTask = myActivity.new parseYouTubeAndYahoo(); However…. You really shouldn’t be instantiating non-static … Read more
I have found this from The Java Tutorials Instance methods can access instance variables and instance methods directly. Instance methods can access class variables and class methods directly. Class methods can access class variables and class methods directly. Class methods cannot access instance variables or instance methods directly—they must use an object reference. Also, class … Read more
Using new Some::Class is called “indirect” method invocation, and it’s bad because it introduces some ambiguity into the syntax. One reason it can fail is if you have an array or hash of objects. You might expect dosomethingwith $hashref->{obj} to be equal to $hashref->{obj}->dosomethingwith(); but it actually parses as: $hashref->dosomethingwith->{obj} which probably isn’t what you … Read more
You don’t need to mess around with descriptors. It’s enough to create a wrapper function inside the __call__() method and return it. Standard Python functions can always act as either a method or a function, depending on context: class MyDecorator(object): def __init__(self, argument): self.arg = argument def __call__(self, fn): @functools.wraps(fn) def decorated(*args, **kwargs): print “In … Read more
As far as I understand at the moment: functions are “global”, which means I do not have to import a package to use functions, they are always there. Methods are bound to packages. Is this correct? No, that’s not correct. There are just a couple of functions from the builtin package which are always available. … Read more