String charAt() Method

The Java String charAt() method retrieves and returns the character at the specified position within a String. In Java, strings are indexed starting from zero, and the valid index range spans from 0 to length() - 1, where length() represents the total number of characters in the string. By utilizing the charAt() method, developers can access and manipulate individual characters within a string by referencing their corresponding index positions.

It is important to note that, it will thrown an IndexOutOfBoundsException if the index is less than zero or greater than equal to the length of the string (index<0 index>=length()).

String Change to Uppercase

String toUpperCase()

The Java String toUpperCase() method allows for the conversion of a string to its uppercase form without the need to create a new variable to store the result. By invoking this method on a string object, the original string is transformed to uppercase characters, while the resulting uppercase string is returned. This provides a convenient and efficient way to modify the case of a string directly without the necessity of extra variable assignments.

String Change to Lowecase

String toLowerCase()

The Java String toLowerCase() method facilitates the conversion of a string to its lowercase form without requiring the creation of a new variable to hold the result. When invoked on a string object, this method modifies the original string by transforming its characters to lowercase, and subsequently returns the resulting lowercase string. This functionality allows for the direct modification of a string's case without the need for additional variable assignments, providing a convenient and efficient approach.

Conclusion

The charAt() method in Java is used to retrieve the character at a specific index within a string. It returns the character value at the given position, allowing easy access to individual characters in a string by their index.