Array to ArrayList: Conveniently Sequence Items

array to arraylistProgrammers are able to build arrays more easily using properties and methods from the ArrayList class. When codes of software already have arrays in the file code, programmers can copy the array to the ArrayList class directly. This lets programmers convert arrays to ArrayLists and use the internal properties and functions for editing the values, as you can see in this Java fundamentals course.

Converting an Array to ArrayList in Java

The computer language Java provides a built in interface for lists, defining an ordered set of items and the operations that you programmers can perform on it. The ArrayList class is one of the actual list implementations. When used together, these provide Java programmers with a convenient way of managing items in a sequence, which you can learn more about by taking this Java course. This is done by taking care of the of the low level item management details while ensuring that performance is efficient.

  • Range View Method

A half open range is returned when you use the range view methods such as the sublist (). This is a sub-list that contains the original list’s items, inclusively from the starting index and exclusively until the ending index. It is not a good idea to modify the original list in any manner through the resulting sub-list. Also the sub-list should be indicated as being transient.

  • Search Methods and Positional Access

The most common methods for positional access are the ‘set()’ and the ‘get()’ methods, which replace and retrieve the listed items at specific indexes. The methods of ‘remove()’ and ‘add()’ provide individual list manipulation based on certain values of the index. Programmers are allowed to search the ArrayList and return an item’s last and first indices using the methods of ‘lastIndexOf()’ and ‘indexOf()’ respectively. For ArrayList, the Java API documentation provides details and descriptions of these procedures.

  • Collection Methods

The collection methods are inherited in ArrayList, which define operations from the Collection interface that manipulate the items in ArrayList. The most important methods are ‘remove()’ and ‘add()’ which allow the removal and insertion of specific ArrayList items. Bulk removals and insertions are also a possibility with the methods of ‘removAll()’ and ‘addALL()’ methods. Other methods report the ArrayList state to the programmers, such as:

‘containsAll()’

‘contains()’

‘isEmpty()’

‘size()’

  • Other Methods of Listing

Java programmers are able to perform generic operations of lists using other list methods. For example programmers can efficiently sort algorithms for list items using the method ‘sort().’ The methods of ‘reverse()’ and ‘shuffle()’ can modify the listed order of items, just as their names imply. Using the method ‘swap(),’ programmers are able to exchange the values of 2 list items.

Converting an Array to an ArrayList in Windows

ArrayList is a .NET class in Windows used for creating a set of values, which you can learn more about by taking this Windows 8 course. The first thing you need to do is add the library \collections\ to your file code. Keep in mind that the library does not really get added by default but is needed for using the class ArrayList. On top of your page with the code file, add this code:

using System.Collections
GO
using System.Collections.Generic;

Next, create a basic array. There are thousands of entries that an array can contain. Using the following code, you can create a 2-value small array:

int[] simpleArray = new int[2]
GO
simpleArray[0] = 1
GO
simpleArray[1] = 2;

You can now go ahead and start copying your array to an ArrayList. Doing this will allow you to use the ArrayList properties and class functions, which are actually more extensive than simple arrays. At the same time, this will also get all your variables converted, as you can see when you check out this course on Windows 8. Use this code for converting your array:

ArrayList myConvertedArray = new ArrayList()
GO
my ConvertedArray.AddRange(mySimpleArray);

A Note on Removing Duplicates from an ArrayList

ArrayLists can contain several hundred or only a few values. If you want duplicates detected, each value is iterated by a .NET loop in the array, checking it against all other array values. Aside from flagging each value for a duplicate, this helps in filtering the contained array values.

To remove duplicates in an ArrayList, enter a few values:

Dim list As New ArrayList
list.Add(1)
list.Add(2)
list.Add(2)
list.Add(3)

Next, the first loop needs to be created. This loop goes through each listed number. It encompasses another loop comparing each of the values to all other array numbers. Here is the code for creating the first loop:

For i As Integer = 0 To list.Count - 1
Dim value = list(i)
Loop

Next, the 2nd loop needs to be set up. This takes the first loop’s values and makes a comparison to all other ArrayList values. Once you find a duplicate, a user gets a message. Here is how to find any duplicate:

For i As Integer = 0 To list.Count - 1
Dim value = list(i)
For j As Integer = 0 To list.Count - 1
If value = list(j) Then
Response.Write("Duplicate Exists")
End If
Loop
Loop

For more on this topic, you might want to check out  this article on Java arrays.