collections

问题 I am trying to duplicate an item in a collection based on the date range. For example, I have a JSON of this: { "title": " 200", "start": "2017-12-20", "endx": "2017-12-25", "equipment": "Chairs", "quantity": 200 } Now I want to duplicate 6x because there are 6 days from 12-20 to 12-25. Like this: { "title": " 200", "start": "2017-12-20", "endx": "2017-12-20", "equipment": "Chairs", "quantity": 200 } { "title": " 200", "start": "2017-12-21", "endx": "2017-12-21", "equipment": "Chairs",

问题 I was playing with some examples of Collections from Oracle website public class Timing { public static void method(){ List numbers = new ArrayList(); for (double i = 1; i <= Double.MAX_VALUE; i++) numbers.add(new Double(i)); Collections.shuffle(numbers); List winningcombination = numbers.subList(0, 10); Collections.sort(winningcombination); } public static void main(String[] args) { long start = System.currentTimeMillis(); method(); long end = System.currentTimeMillis(); System.out.println(

问题 Consider the following classes: public abstract class Token { private List<Token> _Tokens { get; set; } // ReadOnly public is mandatory. How to give protected add-only, index-based access? public ReadOnlyCollection<Token> Tokens { get { return (this._Tokens.AsReadOnly()); } } // AddOnly for derived classes. protected Token AddToken (Token token) { this._Tokens.Add(token); return (token); } } public class ParenthesesToken: Token { // This method is called frequently from public code. public

问题 If I had two iterators I could just write iter1 ++ iter2 and iterators would not be computed until they are needed. Is there any way to chain Iterable instances in the same way? I tried to use iterable1 ++ iterable2 but it causes immediately calculating nested values just like they are added to some structure. Is it possible to avoid this extra calculations and creating extra data structures? 回答1: No. Iterable is just an interface that can be implemented by anything that can be iterated over.

问题 I have a DataGrid which contains informations about products, like NAME and PRICE, Items could be added or removed from DataGrid by Pressing DEL Key down (Remove case). I am using ObservableCollection as DataGrid source, and it looks like this: ObservableCollection<ProductTemporary> result = ProductsTempController.Instance.SelectAll(); Also there is button on my Window which is keeping sum of my product's prices updated all the time, when item is added sum is increased, when item is removed

问题 My issue is I am using the table data source from the dictionary. This dictionary contains more than 20 elements in it. I need to search the element present in the dictionary and I need to scroll that element to a visible cell. My issue is I found the element, but it is out of the visible area. I need to scroll that to a visible area. How can I get the index? 回答1: Short answer? Nope. I know the feeling though, which lead me to... Longer answer? Yes-ish? My search a little while back brought

问题 I have to remove a sublist from the ArrayList and add the same in begining. I am using below code - for(int i =0 ;i <m ; i++){ List<Integer> t = q.subList(j, k); q.removeAll(t); q.addAll(0, t); } I am getting concurrent exception modification on addAll . I tried creating a copy list from q and then calling addAll on that, still it throws the error on same line. for(int i =0 ;i <m ; i++){ List<Integer> t = q.subList(j, k); q.removeAll(t); ArrayList<Integer> q1= new ArrayList<Integer>(q); q1

问题 Hey im just wondering what would be the best collection to use when creating a store for employee details such as name, age address, dob, wages and email address. the store needs all the bare essentials such as add, edit, remove, remove all and searchBy. 回答1: Well you'd probably want a fast search, so a hashing structure with the key as the fiend you want to search by could be the best solution. For example, if you want to search by name, you can create a class like this: public class

问题 Really it's complicated situation for me right now. Here I have to export multidimensional array data into excel which is looks like below image, but I'm unable to make it possible. Please help me to export the multidimensional array data to export in excel. I have an array from relational query like: $array = [ 0 => [ 'name' => 'Devat Karetha', ], 1 => [ 'name' => 'John Doe', 'schools' => [ 0 => [ 'school_name' => 'ABC School', 'school_address' => 'ABC Address', ], 1 => [ 'school_name' =>

问题 I have: class A : IHelp class B : IHelp Then I want to do such thing like: List<A> alist = new List<A>(); List<IHelp> hList = (List<IHelp>) alist; // Error!!! I am a beginner programmer. I will be very grateful to you for detailed answer. Thanks for help! 回答1: You cannot do a cast like this, because it will violate the constraints of the original list. Suppose this works like you said (it actually gives an error, but assume it works): List<A> aList = new List<A>(); List<IHelp> hList = aList;