collections

问题 Is there a .NET equivalent of Java's List.subList() that works on IList<T> ? 回答1: using LINQ list.Skip(fromRange).Take(toRange - fromRange) 回答2: For the generic List<T> , it is the GetRange(int, int) method. Edit: note that this is a shallow copy, not a 'view' on the original. I don't think C# offers that exact functionality. Edit2: as Kamarey points out, you can have a read-only view: List<int> integers = new List<int>() { 5, 6, 7, 8, 9, 10, 11, 12 }; IEnumerable<int> view = integers.Skip(2)

问题 I was just reading about the difference between HashMap and HashTable class in java. There I found a difference that former allow null key and later doesn't privileges for the same. As far as the working of HashMap is concern I know that, it calls hashcode method on key for finding the bucket in which that key value pair is to be placed. Here comes my question: How hashcode for a null value is computed or Is there any default value for hashcode of null key (if so please specify the value)?

问题 I have an array with keys like so: ['asdf12','39342aa','12399','129asg',...] and a collection which has these keys in each object like so: [{guid: '39342aa', name: 'John'},{guid: '129asg', name: 'Mary'}, ... ] Is there a fast way to sort the collection based on the order of keys in the first array? 回答1: var sortedCollection = _.sortBy(collection, function(item){ return firstArray.indexOf(item.guid) }); 回答2: Input: var data1 = ['129asg', '39342aa']; var data2 = [{ guid: '39342aa', name: 'John'

问题 The following code gives me the output in the same order of insertion. I read the javadoc and they did not even talk about the insertion order. Can someone help me to get the right information. import java.util.*; public class hash { public static void main(String[] args) { String str[] = { "japan", "usa", "japan", "russia", "usa", "japan", "japan", "australia"}; int len = 8; Hashtable ht = new Hashtable(); int i = 0; while (i < len) { String c = str[i]; System.out.println("c :" + c); Integer

问题 Many times there is a clear method, that removes all the items from the collections, are these items disposed also. Like, toolStripMenuItem.DropDownItems.Clear(); is sufficient, or should I have to call like that: foreach (ToolStripItem item in toolStripMenuItem.DropDownItems) { toolStripMenuItem.DropDownItems.Remove(item); item.Dispose(); } Edit: Well ToolStripItem is an example not a question, for those who says Clear is enough I found another example, TabControl has also item collection

问题 This question already has answers here : How do I efficiently iterate over each entry in a Java Map? (41 answers) Closed 5 years ago . I need some help, I'm learning by myself how to deal with maps in Java ando today i was trying to get the sum of the values from a Hashmap but now Im stuck. This are the map values that I want to sum. HashMap<String, Float> map = new HashMap<String, Float>(); map.put("First Val", (float) 33.0); map.put("Second Val", (float) 24.0); Ass an additional question,

问题 This question already has answers here : How do I efficiently iterate over each entry in a Java Map? (41 answers) Closed 5 years ago . I need some help, I'm learning by myself how to deal with maps in Java ando today i was trying to get the sum of the values from a Hashmap but now Im stuck. This are the map values that I want to sum. HashMap<String, Float> map = new HashMap<String, Float>(); map.put("First Val", (float) 33.0); map.put("Second Val", (float) 24.0); Ass an additional question,

问题 I have a data like in (string , int) pair. How to store this data in collection object. Both values can be duplicate. Which collection object should i use?? EDIT: How can i access elements separately..?? 回答1: You can use List<KeyValuePair<string,int>> . This will store a list of KeyValuePair 's that can be duplicate. 回答2: You can use List<KeyValuePair<string, int>> if you want to add & remove items, or KeyValuePair<string, int>[] if the number of items is known 回答3: If you want to avoid

问题 I have a data like in (string , int) pair. How to store this data in collection object. Both values can be duplicate. Which collection object should i use?? EDIT: How can i access elements separately..?? 回答1: You can use List<KeyValuePair<string,int>> . This will store a list of KeyValuePair 's that can be duplicate. 回答2: You can use List<KeyValuePair<string, int>> if you want to add & remove items, or KeyValuePair<string, int>[] if the number of items is known 回答3: If you want to avoid

问题 So I am very new to WPF and trying to bind or assign a list of Drink values to a wpf treeview, but don't know how to do that, and find it really hard to find anything online that just shows stuff without using xaml. struct Drink { public string Name { get; private set; } public int Popularity { get; private set; } public Drink ( string name, int popularity ) : this ( ) { this.Name = name; this.Popularity = popularity; } } List<Drink> coldDrinks = new List<Drink> ( ){ new Drink ( "Water", 1 ),