methods

问题 .<digit> means to interpret the number as a float instead of an integer. Can I override .<digit> to let it point the index in an array so that the following will work? c = [1, 2, 3, 4, 5, 6] c.0 # => 1 c.3 # => 4 回答1: No. A method name can't begin with a number in Ruby. More about Ruby method names restrictions here. 回答2: No you can't. That is part of the literal expression for floats. It is not a method call. It is not done at Ruby syntax level. 回答3: As the other answers already told, it is

问题 Is there a way to pass a variable into a method param: <h:commandButton value="Add to Order" actionListener="#{orderBasket.addItems(currentItem.id)}"/> This always seems to pass 0 into the method for some reason. 回答1: That's only possible when you use action instead of actionListener <h:commandButton value="Add to Order" action="#{orderBasket.addItems(currentItem.id)}"/> and you're running a Servlet 3.0 / EL 2.2 capable container (Tomcat 7, Glassfish 3, JBoss 6, etc) and your web.xml is

问题 I would like to do a method chain, for example like this: Car myCar = new Car(); // Chaining myCar.config.engine.cylinders("4"); But how do I do the chaining, without using parentheses in "config" or "engine"? I can only figure out to do it like this: myCar.config().engine().cylinders("4"); 回答1: You can do this by declaring Config property in your Car class. Then Engine property in CarConfig class, like this: public class Car { public CarConfig Config { get; set; } } Then you can chain the

问题 I just finished the Michael Hartl Rails Tutorial. Trying to make something of my own. I am having trouble with getting rails to understand the relationships I'm trying to create. I'll try to simplify this as much as possible. A tree with branches, twigs and leaves would be apt, but... I'll use the parent child format as an example. So naturally I have users, and let's say users create families. So: Class User < ActiveRecord::Base has_many :families has_many :parents has_many :children end

问题 When writing a method, say, inside one of your DAO objects, and you dont want this method to accept certain input, for discussions sake, say it does not allow null arguments. How do you go about implementing that, taking into account this method is likely to be reused in the future by new team members. The way I do it is: In the interface, I document inside the method javadoc that arguments a, b and c cannot be null. Inside the method I check for null values first thing, and if any of a, b or

问题 When writing a method, say, inside one of your DAO objects, and you dont want this method to accept certain input, for discussions sake, say it does not allow null arguments. How do you go about implementing that, taking into account this method is likely to be reused in the future by new team members. The way I do it is: In the interface, I document inside the method javadoc that arguments a, b and c cannot be null. Inside the method I check for null values first thing, and if any of a, b or

问题 I have an Update model which belongs to users. To show all of one user's friends' Updates, I am doing something like: Update.where("user_id" => [array_of_friend_ids]) I know the "right" way of doing things is to create a method to create the above array. I started writing the method but it's only half-working. Currently I have this in my user model: def self.findfriends(id) @friendarray = [] @registered_friends = Friend.where("user_id" => id) @registered_friends.each do |x| @friendarray << x

问题 I have a program for creating a time sheet and when a saved time sheet is loaded by clicking a button on form 1 the data loads to form 2 and then calls a method in form 2 to print the data to form 3. The problem is after the call Form2.Print() there is no data on form 2 if i open it but still works in that the data is printed to form 3. If I remove Form2.Print() the data is loaded on form 2 and i can then click the Print button and if i open form 2 again the data is still in the text boxes.

问题 What would really happen if I don't use x.close() if I want to close a Scanner object or any other object.What is the usage of close() method.Please give example of what happens if we don't use close method. 回答1: The method's purpose really depends on the class it belongs to, but in your example (Scanner) and in most cases that involves some IO operations like file reader, streams, connection and such - the idea behind close() method is to close the connection and release the resource, which

问题 What would really happen if I don't use x.close() if I want to close a Scanner object or any other object.What is the usage of close() method.Please give example of what happens if we don't use close method. 回答1: The method's purpose really depends on the class it belongs to, but in your example (Scanner) and in most cases that involves some IO operations like file reader, streams, connection and such - the idea behind close() method is to close the connection and release the resource, which