[Term Entry] Java ArrayList .removeAll()

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

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+---
+Title: '.removeAll()'
+Description: 'Removes multiple elements from an ArrayList that are also contained in the specified collection.'
+Subjects:
+ - 'Code Foundations'
+ - 'Computer Science'
+Tags:
+ - 'Arrays'
+ - 'Data Types'
+ - 'Java'
+CatalogContent:
+ - 'learn-java'
+ - 'paths/computer-science'
+---
+
+The **`.removeAll()`** method is used for removing multiple elements from instances of the `ArrayList` class.
+
+## Syntax
+
+```pseudo
+ ArrayList1.removeAll(ArrayList2);
+```
+
+- `ArrayList1`: It is the `ArrayList` from which elements will be removed.
+- `ArrayList2`: It is the `ArrayList` containing the elements to be removed from `ArrayList1`.
+
+## Example
+
+In the example below, two `ArrayList` instances, `fallMonths` and `monthsToRemove`, are created to hold `String` type elements. Elements are added to the `fallMonths` using the [`.add()`]
+(https://www.codecademy.com/resources/docs/java/array-list/add) method. Then, `monthsToRemove` is utilized to remove the months - August and September from `fallMonths` using `.removeAll()`. Finally, all elements are removed from `fallMonths` by invoking `.removeAll()` with a reference to itself.
+
+```java
+import java.util.ArrayList;
+
+public class RemoveFallMonths{
+ public static void main(String[] args) {
+
+ ArrayList<String> fallMonths = new ArrayList<String>();
+
+ fallMonths.add("August");
+ fallMonths.add("September");
+ fallMonths.add("October");
+ fallMonths.add("November");
+ fallMonths.add("December");
+
+ ArrayList<String> monthsToRemove = new ArrayList<String>();
+
+ monthsToRemove.add("August");
+ monthsToRemove.add("December");
+
+ // Remove August and December from fallMonths using monthsToRemove
+ fallMonths.removeAll(monthsToRemove);
+
+ System.out.println("After removing specified months: " + fallMonths);
+
+ // Remove all elements from fallMonths
+ fallMonths.removeAll(fallMonths);
+
+System.out.println("After removing all elements: " + fallMonths);
+ }
+}
+```
+
+The output of the above code should look like this:
+
+```shell
+After removing specified months: [September, October, November]
+After removing all elements: []
+```