How to Randomly Select and Display an Item from an ArrayList?

Get random items from ArrayList

Accessing random elements from a list is a common task in programming. In this article, we will explore an efficient way to retrieve random string items from an ArrayList.

Question:

Given an ArrayList containing strings, the goal is to design a mechanism that allows the user to click a button and randomly select a string from the list. The selected string should then be displayed in the message box.

Solution:

The solution involves the following steps:

1. Create a random instance: Instantiate a Random class instance. It is recommended to avoid creating new instances frequently to maintain the stability of random number generation. Consider using static fields:

   <code class="language-c#">static Random rnd = new Random();</code>

2. Generate random index: Generate a random number within the item count range of an ArrayList using a Random instance:

   <code class="language-c#">int r = rnd.Next(list.Count);</code>

3. Retrieve and display random items: Get the selected string from the ArrayList using the generated index and display it in the message box:

   <code class="language-c#">MessageBox.Show((string)list[r]);</code>

Implementation Overview:

1. Create a button in your app.

2. Assign the following event handler to the button's Click event:

   <code class="language-c#">private void button_Click(object sender, EventArgs e)
   {
       int r = rnd.Next(list.Count);
       MessageBox.Show((string)list[r]);
   }</code>

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