collections

问题 I have a code foreach (DataColumn dataTableCol in this.dataTable.Columns) { bool columnFound = false; foreach (GRTColumnView uiColumn in descriptor.UIColumns) { if (dataTableCol.ColumnName.Equals(uiColumn.Name)) { columnFound = true; break; } } if (!columnFound) { if (this.dataTable.Columns.Contains(dataTableCol.ColumnName)) this.dataTable.Columns.Remove(dataTableCol.ColumnName); } } I want to remove some "things" from collection if they aren't found in another collection. When I run the

问题 I have a code foreach (DataColumn dataTableCol in this.dataTable.Columns) { bool columnFound = false; foreach (GRTColumnView uiColumn in descriptor.UIColumns) { if (dataTableCol.ColumnName.Equals(uiColumn.Name)) { columnFound = true; break; } } if (!columnFound) { if (this.dataTable.Columns.Contains(dataTableCol.ColumnName)) this.dataTable.Columns.Remove(dataTableCol.ColumnName); } } I want to remove some "things" from collection if they aren't found in another collection. When I run the

问题 I don't know if it's just too late or what, but I don't see how to do this... What I'm expecting to do, and what the object browser says is there, is this: var oc = new ObservableCollection<T>( new List<T>() ); But ObservableCollection<T> has a single parameterless constructor. The object browser says there is 2 overloads where List and IEnuerable should be able to be passed in. Is there something wrong with my setup? Are the constructors not on the phone version? (that would be strange) If

问题 I been learning about java for some time now and even bought several books to help me along. i am now in at the point in my journey that i want to learn about collections. i am able to use array lists in a very basic ways but i would like to understand how they work when use in conjunction with J radio buttons and other swing components. I been working, watching YouTube videos and reading books such as "Introduction to Java Programming- Comprehensive, 10E" and "Java in a Nutshell - (6th E) O

问题 I am planning to sort keys from a hashmap. I am using a customized sort method. Following code gives me compile-time error on compareTo() method where I am using Set as Collection Set<String> set = map.keySet(); Collections.sort(set, (a, b) -> map.get(a) == map.get(b) ? a.compareTo(b) : map.get(b) - map.get(a)); If I convert Set to List and then sort then everything works fine . List<String> words = new ArrayList<>(map.keySet()); Collections.sort(words, (a, b) -> map.get(a) == map.get(b) ? a

问题 What is the necessity to introduce Pair class when Hashmap can do the same job? I see Pair being introduced to Java version 8 回答1: Your choice of which class to use is not just a message to your computer. It's also a message to future developers - people who will maintain your code in the future, or even you yourself in a few months time. By choosing whether to declare a particular variable as either HashMap or Pair , you're telling those future developers something. It's EITHER This variable

问题 I am trying to use Fluent-Nibernate with wpf that require Observable collections (implement the INotifyCollectionChanged interface). At uNHAddins: Unofficial addins for NHibernate i found the uNhAddIns.WPF.Collections.Types.ObservableListType<T> that implements INotifyCollectionChanged . It can be configured in Fluent-Nibernate like this namespace FluentNHibernateTutorial.Mappings { public class StoreMap : ClassMap<Store> { public StoreMap() { Id(x => x.Id); Map(x => x.Name); HasManyToMany(x

问题 I am trying to use Fluent-Nibernate with wpf that require Observable collections (implement the INotifyCollectionChanged interface). At uNHAddins: Unofficial addins for NHibernate i found the uNhAddIns.WPF.Collections.Types.ObservableListType<T> that implements INotifyCollectionChanged . It can be configured in Fluent-Nibernate like this namespace FluentNHibernateTutorial.Mappings { public class StoreMap : ClassMap<Store> { public StoreMap() { Id(x => x.Id); Map(x => x.Name); HasManyToMany(x

问题 I tried doing: str = "" "".join(map(str, items)) but it says str object is not callable. Is this doable using a single line? 回答1: Use string join() method. List: >>> l = ["a", "b", "c"] >>> " ".join(l) 'a b c' >>> Tuple: >>> t = ("a", "b", "c") >>> " ".join(t) 'a b c' >>> Non-string objects: >>> l = [1,2,3] >>> " ".join([str(i) for i in l]) '1 2 3' >>> " ".join(map(str, l)) '1 2 3' >>> 回答2: The problem is map need function as first argument. Your code str = "" "".join(map(str, items)) Make

问题 This question already has answers here : Properly removing an Integer from a List<Integer> (8 answers) Closed 4 years ago . I have following two scenarios: 1. int value as parameter int intNum = 2; List<Integer> list = new ArrayList<Integer>(); list.add(1); list.add(2); list.add(3); list.remove(intNum); System.out.println(list.size()); // output: 2 2. long value as parameter long longNum = 2; List<Integer> list = new ArrayList<Integer>(); list.add(1); list.add(2); list.add(3); list.remove