methods

问题 Have a class Car with a public method public Car myself() { return this; } Have a subclass Ferrari , and a variable foo that contains a Ferrari object. Finally, Ferrari bar = foo.myself(); This will warn you, because the method myself() returns a Car object, rather than the expected Ferrari . Note: I know that the example is stupid because you'd just do bar = foo . It's just an example. Solutions: Override the myself() method in Ferrari . Cast the Car object to a Ferrari object when assigning

问题 How does one present a UIAlertController from another class? I want to know how can you capture the action of an "ok" button in a UIAlertController that was created in Class B but presented in Class A. This is how I call the method that created the Alert on class "ErrorHandler" from ClassA: ErrorHandler *handler = [[ErrorHandler alloc] init]; [self presentViewController:[handler alertWithInternetErrorCode] animated:YES completion:nil]; And this is the implementation of

问题 Is there a way to add a description to my methods in Xcode iOS project so I can see quick details when clicking on a desired method with OPTION + click like it can be done on Apple's API's methods (case bellow)? Thanks! 回答1: If I understand right than all of this tools are for generating documentation and not for adding method's description. Am I right? 来源： https://stackoverflow.com/questions/10530695/show-method-definition-description-in-xcode-4

问题 I'm wondering if there is a way to check if a string is containing a letter. If there is an NSString = @"street 12" I want it to return YES and if NSString = @"12.12,23.23" I want it to return NO Is there a method that handles this made by Apple or do I have to make it myself? 回答1: Here's one way: NSString *someString = ... // the string to check NSRange match = [someString rangeOfCharacterFromSet:[NSCharacterSet letterCharacterSet] options:0 range:NSMakeRange(0, someString.length)]; if

问题 I would like to go from this list: my_list = [u'a','b','c',1,2,3] ...to this string, which maintains the quotes (for creating a sql statement): my_string = "'a', 'b', 'c', 1, 2, 3" This method works, but it sure is ugly! my_string = str(my_list).replace('[','').replace(']','').replace('u','') Is there a nicer way? What's wrong with heaping up the replaces - that can't be right!? 回答1: disclaimer: you should NOT be preparing SQL using plain string manipulation! use a library appropriate for the

问题 I am currently working on this project that plays the high low dice game. I am stuck on how to use the returned char from getHighLow and the returned int from getBet and getRoll in determineWinnings . This is my first year learning Java currently, so any help would be appreciated. Thank you in advance for any help you can give! public static void main(String[] args) { Scanner keyboard = new Scanner(System.in); int currentPool = 100; getBet(keyboard, currentPool); getHighLow(keyboard); getRoll

问题 Is there a gem or a library to get ruby 1.9 methods like [1, 2, 3].combination(2) [1, 2, 3].permutation(2) [1, 2, 3].product([1, 2, 3]) [1, 2, 3, 4, 5].cycle 回答1: This is exactly the goal of my gem backports. It implements in pure Ruby all the new features of Ruby 1.8.7 and many of Ruby 1.9.x and 2.0. This of course includes #combination , #permutation , #product and #cycle . You can, for example: require 'backports/1.8.7/array/combination' [1, 2, 3].combination(2) # => works, even in Ruby 1

问题 What is a better approach for implementing converter from DTO to Entity? Using factory with static methods to convert or using instance Converter object? 回答1: Finally I ended with instance Converter objects as they may be mocked, that is better for testing 来源： https://stackoverflow.com/questions/13176707/static-methods-to-transform-dto-to-entity

问题 Sorry if this already exists somewhere in the question archives, but I'm not sure how to ask it and searching didn't lead to any great revelations. In Python (2.6.x) I have created a class class timetuple(object): def __init__(self): self.weekday = 6 self.month = 1 self.day = 1 self.year = 2011 self.hour = 0 self.min = 0 self.sec = 0 def jd(self): self.jd = julian_date(self) def julian_date(obj): (Code to calculate a Julian Date snipped) start = timetuple() start.day = 23 start.month = 2

问题 I want to calculate the position of two particles that will be constantly reacting between each other. My problem is that I need to bring my particle listParticle array from my readData() to my main(String[] args) method. I have tried making the array of particles a global variable, but it always forces me to make it static and then my code does not work. My program reads from a file, with the data as such: 2 1 1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2 1 1.5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 The