Java ArrayList

Java ArrayList is a resizable array implementation of the List interface in Java Collections framework. It allows us to store elements in the list and provides dynamic resizing, which makes it very useful for handling large sets of data.

Declaration

To declare an ArrayList in Java, you first need to import the java.util package. After that, you can create an ArrayList object using the ArrayList class as shown below:

import java.util.ArrayList;

ArrayList<String> list = new ArrayList<String>();

Here, String represents the type of elements that the list can hold. You can replace it with any other data type or class name based on your requirements.

Adding Elements

You can add elements to the list using the add() method. It appends the specified element to the end of the list.

list.add("Element 1");
list.add("Element 2");
list.add("Element 3");

You can also insert elements at a specific position using the add(index, element) method.

list.add(1, "Inserted Element");

Removing Elements

You can remove elements from the list using the remove() method. It removes the first occurrence of the specified element from the list.

list.remove("Element 1");

You can also remove elements at a specific position using the remove(index) method.

list.remove(0);

Accessing Elements

You can access elements in the list using the get(index) method. It returns the element at the specified index.

String element = list.get(0);

Iterating the List

You can iterate over all the elements in the list using a for-each loop or an iterator.

for (String element : list) {
    System.out.println(element);
}

Iterator<String> iterator = list.iterator();
while (iterator.hasNext()) {
    String element = iterator.next();
    System.out.println(element);
}

Conclusion

ArrayList is a powerful data structure that provides dynamic resizing and various methods to add, remove, and access elements from the list. It is widely used in Java programming for handling collections of objects.