How to find the first and last character of a string in Java

Given a string str, the task is to print the first and the last character of the string. Examples:

Input: str = “GeeksForGeeks” Output: First: G Last: s Explanation: The first character of the given string is ‘G’ and the last character of given string is ‘s’. Input: str = “Java” Output:  First: J Last: a Explanation: The first character of given string is ‘J’ and the last character of given string is ‘a’.

Method 1: Using String.charAt() method

• The idea is to use charAt() method of String class to find the first and last character in a string. 
• The charAt() method accepts a parameter as an index of the character to be returned.
• The first character in a string is present at index zero and the last character in a string is present at index length of string-1.
• Now, print the first and last characters of the string.

Below is the implementation of the above approach: 

Java

// Java program to find first
// and last character of a string

class GFG {

    // Function to print first and last
    // character of a string
    public static void
    firstAndLastCharacter(String str)
    {

        // Finding string length
        int n = str.length();

        // First character of a string
        char first = str.charAt(0);

        // Last character of a string
        char last = str.charAt(n - 1);

        // Printing first and last
        // character of a string
        System.out.println("First: " + first);
        System.out.println("Last: " + last);
    }

    // Driver Code
    public static void main(String args[])
    {
        // Given string str
        String str = "GeeksForGeeks";

        // Function Call
        firstAndLastCharacter(str);
    }
}

Output

First: G
Last: s

Method 2: Using String.toCharArray() method

• The idea is to first convert the given string into a character array using toCharArray() method of String class, then find the first and last character of a string and print it.

Below is the implementation of the above approach: 

Java

// Java program to find first
// and last character of a string

class GFG {

    // Function to print first and last
    // character of a string
    public static void
    firstAndLastCharacter(String str)
    {
        // Converting a string into
        // a character array
        char[] charArray = str.toCharArray();

        // Finding the length of
        // character array
        int n = charArray.length;

        // First character of a string
        char first = charArray[0];

        // Last character of a string
        char last = charArray[n - 1];

        // Printing first and last
        // character of a string
        System.out.println("First: " + first);
        System.out.println("Last: " + last);
    }

    // Driver Code
    public static void main(String args[])
    {
        // Given string str
        String str = "GeeksForGeeks";

        // Function Call
        firstAndLastCharacter(str);
    }
}

Output

First: G
Last: s

Time complexity: O(1)
Auxiliary space: O(n) because it is using extra space for charArray