Java ArrayList get() Method

The get() method is a fundamental operation of the Java ArrayList class. It allows you to access elements by their index efficiently, making it a critical part of ordered, index-based data handling in Java. Understanding how get() works is essential for reading or using data stored in an ArrayList.

What Is the get() Method in ArrayList?

• The get() method retrieves the element at a specific index in the list.
• It returns the element stored at the given position.
• The index is zero-based (the first element is at index 0).
• You can use get() in a loop to access or display all elements.

Syntax

public E get(int index)

Where:

• E is the data type of the elements stored in the list.
• index is the position of the item you want to access (starts from 0).

Parameters

Parameter	Description
index	Index of the element to retrieve (0-based)

• The index must be between 0 and size() - 1.

Return Value

• Returns the element at the specified position in the ArrayList.
• The data type returned matches the list’s declared type.

Exceptions

• IndexOutOfBoundsException: Thrown if the specified index is out of range (less than 0 or greater than or equal to the list size).
• There are no other checked exceptions.

How Does get() Work Internally?

• ArrayList is backed by an internal array, so get() operates in constant time O(1).
• The method simply returns the element at the specified index.
• Internally, it checks if the index is valid; if not, it throws an exception.
• Efficient for both reading and iterating through lists.

Examples of the get() Method

1. Get Elements from an ArrayList

import java.util.ArrayList;

public class Main {
    public static void main(String[] args) {
        ArrayList<String> cities = new ArrayList<>();
        cities.add("Delhi");
        cities.add("Mumbai");
        cities.add("Chennai");

        // Gets the element at index 1 ("Mumbai")
        String city = cities.get(1); 
        System.out.println("City at index 1: " + city);
    }
}

Output:

City at index 1: Mumbai

2. Using get() in a Loop

import java.util.ArrayList;

public class Demo {
    public static void main(String[] args) {
        ArrayList<Integer> numbers = new ArrayList<>();
        numbers.add(10);
        numbers.add(20);
        numbers.add(30);

        for (int i = 0; i < numbers.size(); i++) {
            System.out.println("Element at index " + i + ": " + numbers.get(i));
        }
    }
}

Output:

Element at index 0: 10
Element at index 1: 20
Element at index 2: 30

3. Handling IndexOutOfBoundsException

import java.util.ArrayList;

public class Example {
    public static void main(String[] args) {
        ArrayList<String> list = new ArrayList<>();
        list.add("A");
        list.add("B");

        try {

            // Index 2 is out of bounds (size is 2)
            System.out.println(list.get(2)); 
        } catch (IndexOutOfBoundsException e) {
            System.out.println("Error: " + e.getMessage());
        }
    }
}

Output:

Error: Index 2 out of bounds for length 2

Important Notes

• Indexing starts from 0 (not 1).
• Always ensure you are accessing a valid index within the list’s current size().
• If you call get() with an invalid index, your program will throw an exception and may stop execution.
• Use get() when you need random access or want to read by position.
• For performance, get() is much more efficient than in linked structures like LinkedList.

Summary

Aspect	Details
Method Purpose	Access element at a specific index in ArrayList
Syntax	list.get(int index)
Return Value	Element at the given index (type E)
Index Base	Zero-based (first element at 0)
Throws Exception	IndexOutOfBoundsException if index is invalid
Typical Use Cases	Reading by position, iteration, random access

Typical Use Cases

• Accessing or displaying items by index.
• Retrieving data in loops.
• Reading user-selected elements from lists.
• Implementing algorithms that need random or indexed access to elements.