Henry Instructions - NET Data Structure Object Silent Single List (4)
Han Rui (06/15/2003)
3.10 Other properties
This article does not fully implement all ILIST interface methods and properties, but it is still to be declared as follows. Since the single-chain table class in this article does not provide a built-in thread synchronization (all finished, what is the next time I say. Haha), Issynchronized returns to false, Syncroot returns to the reference. The number of enumerations do not have an exclusive access to the collection; therefore, enumerating a collection in essence is not a thread security process. Even when synchronizing the collection, other threads can still modify the collection, which will cause an enumeration number to trigger an exception. To ensure thread security during enumeration, you can lock a collection through the SYNCLOCK throughout the enumeration process, or capture exceptions caused due to changes in other threads. The processing like the SSLIST class, each lock will block all objects, to provide a smaller thread safety, we will continue to discuss later.
Public overridable readonly property issynchronized () as boolean _
Implements ilist.issynchronized
Get
Return False
END GET
End Property
Public overridable readonly property syncroot () as object _
Implements ilist.syncroot
Get
Return ME
END GET
End Property
The isFixedSize property refers to a value when analog is implemented, which indicates whether the ilist has a fixed size. The chain table category does not have a fixed size, so the return is of course FALSE.
Public overridable readonly property isfixedsize () as boolean _
Implements IList.isfixedsize
Get
Return False
END GET
End Property
The isReadOnly property refers to a value indicating whether iList is read-only when an implementation is implemented. Of course, returning false.
Public overridable readonly property isreadonly () as boolean _
Implements IList.isreadOnly
Get
Return False
END GET
End Property
4. Call the example
Above we have analyzed in detail with the implementation of the SSLIST class, now come and see its structure, as shown in Figure 2:
Figure 2 structure (including two nested classes)
So how do you use our single-link table? In fact, it is easy, it is quite similar to the usage method of the ArrayList class, but we don't have to set the length of the list. In another VB file, we will operate the SLLIST class:
'Example of use
DIM LST AS New SLLIST ()
Try
Lst.Add ("Henry") Add
Lst.Add ("jjj")
Lst.Insert (1, "kkk") 'insert
Lst.Remove ("jjj") 'Press value to delete
Lst.Removeat (1) 'Delete according to the index number
LST (0) = "jerry" "change
DIM I as integer = lst.indexof ("jjj") 'Removes the induced number' multiple loop traverses
DIM CollectionItem As Object
Dim loopcounter as integer
DIM ENUMCOLLECTION As IEnumerator
'The first
For Each CollectionItem in LST
Console.writeline (CollectionItem)
NEXT
'Second
For loopCounter = 0 to Lst.count - 1
Console.WriteLine (LST.Item (LoopCounter))
NEXT
'Third
Enumcollection = Lst.GeteNumerator ()
Do While Enumcollection.Movenext
Console.writeline (Enumcollection.current)
Loop
Catch exception
MsgBox (ex.toswoting)
END TRY
Now let's take a look at the role of Version:
'Third
Enumcollection = Lst.GeteNumerator ()
Lst.Add ("Kelly")
Do While Enumcollection.Movenext
Console.writeline (Enumcollection.current)
Loop
At this point, you will get an exception, prompt to:
System.invalidOperationException: This chain list has changed after the enumerator was created.
Isn't this an error message we defined in the VerifyListisunchanged method? Now everyone will understand why we have the corresponding prompt text when you operate ArrayList or other .NET classes. Imaginate the error prompts that we define our definition prompts will also be captured in this example. Please test it yourself.
5. Summary and Prospect
In this article, you will go deep into the implementation of the Collections collection class, and we use ArrayList (I am also, huh) in the actual work. However, the insertion of the linked list is much higher than that of ArrayList (single-linked list plus the front flute pointer will increase efficiency), of course, the ability of the index value is not as good as ArrayList. When we deal with certain lists of frequently deleting and insert, we are still worth considering whether to use a linked list to implement our needs.
Limited to space and time, for sorting, synchronization, etc. ARRAYLIST has no excessive involvement, interested friends, please continue to pay attention to my column. see you later!
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