[Edit] Java: .set() (#7097)

* [Edit] Java: .set()

* minor content fix

---------

Author: Sriparno08

content/java/concepts/array-list/terms/set/set.md

@@ -1,61 +1,149 @@
 ---
 Title: '.set()'
-Description: 'Replaces the element present in a specified position in an ArrayList.'
+Description: 'Replaces the element present at a specified position with another element in an ArrayList.'
 Subjects:
   - 'Code Foundations'
   - 'Computer Science'
 Tags:
   - 'Arrays'
   - 'Data Types'
+  - 'Index'
+  - 'Methods'
 CatalogContent:
   - 'learn-java'
   - 'paths/computer-science'
 ---
 
-The **`.set()`** method replaces an element at a specified position with another element in an `ArrayList` instance. After execution, the replaced element is returned.
+In Java, the **`.set()`** [method](https://www.codecademy.com/resources/docs/java/methods) replaces the element present at a specified position with another element in an `ArrayList`. After execution, the method returns the replaced element.
+
+Understanding how `.set()` works is crucial when dealing with mutable lists in Java, especially when updating or modifying elements during processing.
 
 ## Syntax
 
 ```pseudo
-arrayListInstance.set(index, newElement);
+arrayList.set(index, element);
 ```
 
-An element at a specified `index` is replaced in an `arrayListInstance` with the `newElement`.
+**Parameters:**
+
+- `index`: The position in the list where the element should be replaced.
+- `element`: The new element that will replace the old one at the given index.
+
+**Return value:**
 
-> **Note:** The `newElement` must be of the same [data type](https://www.codecademy.com/resources/docs/java/data-types) as the rest of the elements in `arrayListInstance`. Otherwise, an error will occur.
+The `.set()` method returns the replaced element.
 
-## Example
+> **Note:** The `element` must be of the same [data type](https://www.codecademy.com/resources/docs/java/data-types) as the rest of the elements in the `arrayList`. Otherwise, an [error](https://www.codecademy.com/resources/docs/java/errors) will occur.
 
-In the example below, an empty `ArrayList` instance `studentList` is created and can hold `String`-type elements. Next, a few elements are added with the [`.add()`](https://www.codecademy.com/resources/docs/java/array-list/add) method. Lastly, two students are replaced with the `.set()` method:
+## Example 1: Basic Usage of `.set()`
+
+This example uses the `.set()` method to replace elements at multiple positions in an `ArrayList`:
 
 ```java
 import java.util.ArrayList;
 
 public class Students {
   public static void main(String[] args) {
-
+    // Create an ArrayList
     ArrayList<String> studentList = new ArrayList<String>();
 
-    // Add new values to the studentList
+    // Add values to the ArrayList
     studentList.add("John");
     studentList.add("Lily");
     studentList.add("Samantha");
     studentList.add("Tony");
 
-    // `.set()` method returns replaced element's value
+    // Replace elements at multiple positions in the ArrayList
     String replacedStudentOne = studentList.set(1, "David");
     String replacedStudentTwo = studentList.set(2, "George");
 
-    // Output updated ArrayList and replaced elements
+    // Print the updated ArrayList
     System.out.println("Updated ArrayList: " + studentList);
-    System.out.println("Replaced Elements: " + replacedStudentOne + " and " + replacedStudentTwo);
   }
 }
 ```
 
-The output should look like this:
+Here is the output:
 
 ```shell
 Updated ArrayList: [John, David, George, Tony]
-Replaced Elements: Lily and Samantha
 ```
+
+## Example 2: Using `.set()` with Integers
+
+This example uses the `.set()` method to replace an integer with another integer in an `ArrayList`:
+
+```java
+import java.util.ArrayList;
+
+public class Example2 {
+  public static void main(String[] args) {
+    // Create an ArrayList
+    ArrayList<Integer> numbers = new ArrayList<>();
+
+    // Add values to the ArrayList
+    numbers.add(10);
+    numbers.add(20);
+    numbers.add(30);
+
+    // Replace the second element
+    numbers.set(1, 99);
+
+    // Print the updated ArrayList
+    System.out.println(numbers);
+  }
+}
+```
+
+Here is the output:
+
+```shell
+[10, 99, 30]
+```
+
+## Example 3: Handling Index Errors
+
+This example attempts to replace an element at an out-of-bounds index using the `.set()` method, resulting in an `IndexOutOfBoundsException`:
+
+```java
+import java.util.ArrayList;
+
+public class Example3 {
+  public static void main(String[] args) {
+    // Create an ArrayList
+    ArrayList<String> colors = new ArrayList<>();
+
+    // Add values to the ArrayList
+    colors.add("Red");
+    colors.add("Green");
+
+    try {
+        colors.set(5, "Blue");
+    } catch (IndexOutOfBoundsException e) {
+        System.out.println("Error: " + e.getMessage());
+    }
+  }
+}
+```
+
+In this example, the `try...catch` block is used to catch the exception and display the error message.
+
+Here is the output:
+
+```shell
+Error: Index 5 out of bounds for length 2
+```
+
+## Frequently Asked Questions
+
+### 1. Can `.set()` be used to add new elements to a list?
+
+No. The `.set()` method replaces an existing element at a given index. To insert a new element, use `.add()` instead.
+
+### 2. Is `.set()` available for all collections in Java?
+
+No. `.set()` is only available for classes that implement the `List` interface, such as `ArrayList`, `LinkedList`, and `Vector`.
+
+### 3. Does `.set()` change the size of the list?
+
+No. `.set()` only modifies the value at the specified index.