The IList Interface: Enabling Data Binding in .NET

Encoding Code 128 Code Set C in .NET The IList Interface: Enabling Data Binding
The IList Interface: Enabling Data Binding
Code 128 Code Set A Generation In Visual Studio .NET
Using Barcode generation for .NET framework Control to generate, create Code 128 image in .NET applications.
The IList interface lets you treat a collection as an ordered, indexed set of data items The IList interface is one of the most important interfaces in data binding, because complex data-bound controls can only be bound to collections that implement IList Using an IList interface reference to a collection, you can manage the collection's data by adding, removing, inserting, and accessing items The IList interface is a key interface that enables runtime data binding in most Windows controls IList derives from ICollection, so you need to also implement ICollection and IEnumerable to support IList IList defines a set of members that further defines a collection as an ordered, indexed collection of data that can be accessed and modified in a random order The good news is that you should never have to implement the IList interface yourself in a NET 20 application, because theList<T> generic type provides a full implementation for any type that you want to contain in a collection However, you many need to consume the interface to use a collection within your application code or in a custom data-bound control The members of the IList interface are described in Tables 74 and 75 and in the following paragraphs
Code-128 Recognizer In .NET Framework
Using Barcode scanner for VS .NET Control to read, scan read, scan image in VS .NET applications.
Table 74 IList Interface Properties
Draw Barcode In .NET Framework
Using Barcode maker for Visual Studio .NET Control to generate, create barcode image in Visual Studio .NET applications.
Name IsFixedSize Type Boolean Description True if items cannot be added or removed from the collection, false otherwise If true, the collection size is pre-allocated at construction time and cannot be changed If that is the case, the collection should throw an exception if the Add, Insert, Remove, RemoveAt, or Clear methods are called False indicates that the collection can be modified by the consumer This is a read-only property IsReadOnly Boolean True if the items in the collection cannot be edited after the collection is constructed, false otherwise If IsReadOnly is true, then the constraints implied by IsFixedSize also apply When this property is false, the items in the collection can be edited by the consumer This is a read-only property this[int index] Object Lets you index into the collection using array notation with an index position to read or assign objects into the collection Also know as the Item property, because the convention in Visual Basic is to expose a parameterized Item property that is the default property, which is how indexers are exposed in Visual Basic that are written in C#
Bar Code Scanner In VS .NET
Using Barcode reader for VS .NET Control to read, scan read, scan image in .NET applications.
Table 75 IList Interface Methods
Paint ANSI/AIM Code 128 In C#.NET
Using Barcode creation for .NET framework Control to generate, create Code 128 image in .NET applications.
Method int Add (object item) Description Adds a new item into the collection at the end of the list and returns the index of the new item in the collection
Code 128 Code Set C Maker In .NET
Using Barcode printer for ASP.NET Control to generate, create Code 128B image in ASP.NET applications.
This document was created by an unregistered ChmMagic, please go to http://wwwbisentercom to register it Thanks
Code 128 Code Set B Generation In VB.NET
Using Barcode encoder for VS .NET Control to generate, create ANSI/AIM Code 128 image in .NET applications.
Method void Clear ()
Generate Data Matrix In Visual Studio .NET
Using Barcode generation for VS .NET Control to generate, create ECC200 image in Visual Studio .NET applications.
Description Empties the collection of all items, removing the references to all the contained objects, thus making them eligible for garbage collection Checks to see if it can find the object instance passed in as a parameter within the collection If it finds the object, the method returns true If no matching object reference is found, the method returns false Tries to locate the object reference passed in as a parameter within the collection If the object is in the collection, the index of it within the collection is returned If the object isn't in the collection, the method should return 1 Adds a new item to the collection by inserting it at a particular location The desired index is provided as a parameter, along with a reference to the object The item currently residing at that index and any that follow it have their position incremented by one If the specified index is the size of the collection, the item is appended at the end of the list, which is the same effect as calling Add Removes an object reference from the collection by matching against the object reference passed in If the specified object is found, it is simply removed from the list, and any items that follow it in the list have their index decremented by one Removes an item from the collection based at the index specified by the method parameter Any items that follow it in the collection will have their index decremented by one
Barcode Encoder In .NET
Using Barcode creation for .NET Control to generate, create bar code image in VS .NET applications.
bool Contains (object item)
Barcode Creator In Visual Studio .NET
Using Barcode maker for .NET Control to generate, create barcode image in Visual Studio .NET applications.
int IndexOf (object item)
Painting GS1 - 13 In VS .NET
Using Barcode drawer for .NET Control to generate, create EAN-13 Supplement 5 image in VS .NET applications.
void Insert (int index, object item)
Identcode Drawer In .NET Framework
Using Barcode maker for Visual Studio .NET Control to generate, create Identcode image in VS .NET applications.
void Remove (object item)
Generating Bar Code In Java
Using Barcode creator for Java Control to generate, create barcode image in Java applications.
void RemoveAt (int index)
Generating Code 3 Of 9 In C#
Using Barcode printer for Visual Studio .NET Control to generate, create Code-39 image in VS .NET applications.
The IList interface adds the methods and properties to a collection that make it behave like a full-fledged random access, editable, and modifiable collection of data As discussed in an earlier chapter, Windows Forms data binding is two waymany data-bound controls not only support presenting data for viewing, but also let the user edit the data within the control, resulting in updates to the underlying data source You can access any item in the collection through the bound control at any time because of the stateful model of Windows Forms and controls, so random access to the collection's contents becomes important If you only need to support one-way data binding (forward-only, read-only iteration through the data items), IEnumerable would be enough to get to all the data items, and late bound discovery could be used to display the data As mentioned before, the BindingSource component is able to iterate over collections that only implement IEnumerable to put those objects into its own internally maintained list of items, at which point you can data bind in Windows Forms to the BindingSource component because it implements theIList interface The Add, Insert, Remove, RemoveAt, and Clear methods make it easy to manage the items in the collection as a variable-length ordered list (this should be fairly intuitive from the descriptions in Table 74) The Contains and IndexOf methods, in conjunction with the indexer, let you have random access to the collection's contents to either read data out for presentation or to modify the contents of a given position in the list The IsFixedSize and IsReadOnly properties are intended to give you an indication of whether you can modify the contents of the collection, and if so, to what degree Because the other members of IList are specifically designed to support modifying the list, it is rare that you will run into a collection that is never modifiable, and usually the default is that they are modifiable However, you might find collections that support switching the collection into a read-only mode or a frozen-size mode Those properties let you check for the presence of that mode before trying to modify the contents of the collection, which should result in an exception if the collection is marked as read-only or fixed-size Working with a collection that implements IList from code is straightforward You can declare an instance of the collection, add items to it with the Add method, locate items with IndexOf, determine how many are in the collection through the implemented Count member of the inherited ICollection interface, iterate over all of the collection's items and index into the collection with the IList indexer, or access the items through the inherited support from the IEnumerable interface, all in a very few lines of code:
Decode EAN-13 In .NET Framework
Using Barcode scanner for .NET framework Control to read, scan read, scan image in VS .NET applications.
List<int> myCollection = new List<int>(); myCollectionAdd(42); myCollectionAdd(38); DebugAssert(myCollectionIndexOf(42) == 0); for (int i = 0; i < myCollectionCount; i++)
USS Code 39 Generator In Visual Basic .NET
Using Barcode creator for .NET framework Control to generate, create Code 39 image in Visual Studio .NET applications.
This document was created by an unregistered ChmMagic, please go to http://wwwbisentercom to register it Thanks { myCollection[i] = 99; } foreach (int val in myCollection) { ConsoleWriteLine("Value = {0}", val); }
Barcode Drawer In VB.NET
Using Barcode creation for .NET Control to generate, create barcode image in .NET framework applications.
This code uses an instance of the List<T> generic type, which implementsIList and all of its base interfaces for you for any type parameter that you specify As mentioned earlier in the book, when you declare a variable of a generic type with a type parameter, such as the declaration of myCollection in this code withint as the type parameter, you are really creating a new type that is a strongly typed list of integers, as well as declaring an instance of that type, all in one line of code As long as a collection supports the IList interface, you will be able to bind it to any of the NET Framework Windows Forms controls that support data binding, using either simple binding (Binding objects) or complex data binding (DataSource and DataMember properties) If the control supports modifying the collection (such as the DataGridView), you can add items to the collection, remove them, or edit the values of an item exposed through properties on the contained objects Internally, the data-binding code of a control iterates over the collection's contents and indexes into it using the IList methods and properties Once the control has obtained access to an item in the collection, it can use the PropertyDescriptor class to dynamically discover information about the properties of the items in the collection and can use those to populate whatever properties or display elements of the control are bound to the data See the property descriptors for more information and the samples in 8 for implementing custom data-bound controls later section on
Create Barcode In Java
Using Barcode printer for Java Control to generate, create bar code image in Java applications.
One limitation of the IList interface with respect to data binding is that although it is sufficient to allow the data to be displayed and support updates, additions, and deletions from the bound control, it doesn't support all scenarios for the collection's modifiable data Specifically, if the data collection is changed programmatically by code outside of the bound control, the control won't know of those changes, and the data it displays will be out of sync with the actual data contained by the collection (see the examples in 9 for more information on this) To remedy this shortcoming, you have to implement IBindingList in collections that you want to use for data binding (described later in this chapter) You will also want to implement the INotifyPropertyChanged interface on the data item's object type Like its parent interfaces, IList also has a generic cousin interface, IList<T>, that you should implement if your collection will be a strongly typed collection of objects IList<T> only defines the Insert, IndexOf, RemoveAt, and indexer members, because the otherIList members are inherited from ICollection<T> The List<T> generic collection type implements these generic interface versions for you as well
Scanning Barcode In Java
Using Barcode decoder for Java Control to read, scan read, scan image in Java applications.
This document was created by an unregistered ChmMagic, please go to http://wwwbisentercom to register it Thanks
ECC200 Decoder In .NET
Using Barcode recognizer for .NET Control to read, scan read, scan image in VS .NET applications.