Java String charAt() example

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In this guide, you will learn about the String charAt() method in Java programming and how to use it with an example.

1. String charAt() Method Overview

Definition:

The charAt() method in Java's String class returns the character at the specified index of a given string.

Syntax:

str.charAt(int index)

Parameters:

- index: The zero-based index of the character to retrieve from the string.

Key Points:

- The charAt() method belongs to the String class.

- The index is zero-based, meaning the first character is at index 0, the second at index 1, and so forth.

- If you provide an index that's out of bounds (negative or greater than or equal to the string's length), a StringIndexOutOfBoundsException is thrown.

- This method is especially handy for character-by-character string parsing or operations.

2. String charAt() Method Example

public class CharAtExample {
    public static void main(String[] args) {
        String phrase = "Java Programming";

        // Retrieve the 5th character of the string
        char fifthCharacter = phrase.charAt(4);
        System.out.println("The 5th character is: " + fifthCharacter);

        // Attempt to retrieve a character beyond the string's length
        try {
            char outOfBoundsCharacter = phrase.charAt(50);
            System.out.println("Character: " + outOfBoundsCharacter);
        } catch (StringIndexOutOfBoundsException e) {
            System.out.println("Error: Index out of bounds.");
        }
    }
}

Output:

The 5th character is: a
Error: Index out of bounds.

Explanation:

In our example, we first extract the 5th character (index 4) of the string "Java Programming", which is the letter 'a'. 

Next, we purposefully try to extract a character using an out-of-bounds index. This throws a StringIndexOutOfBoundsException, which we catch and print an error message.

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