Java Program to Find First Uppercase Letter in a String by Using Recursion

Prerequisite: Recursion in Java

In the previous article, we have discussed about Java Program to Find First Lowercase Letter in a String by Using Recursion

In this program we are going to see how to find first uppercase in a string using by recursion in Java programming language.

Java Program to Find First Uppercase Letter in a String by Using Recursion

Let’s see an example to understand it.

Lets assume there is a string “i LoVe JaVa”

The first uppercase letter is 'L'

Now let’s see different ways to find first uppercase in a string by using recursion.

By Using Static Input and Recursion
By Using User Input and Recursion

Method-1: Java Program to Find First Uppercase Letter in a String By Using Static Input and Recursion

Approach:

Declare and initialize a String variable ‘str’ as “i LoVe JaVa”
Call a user defined method firstuppercase() and pass the string ‘str’ and the 1^st index ‘0’ as parameter.
Inside the user defined method we will check if the first character is uppercase or not.
If the 1^st char is uppercase then return that value else call the firstuppercase() method recursively to find the first uppercase value.
If the string has no uppercase value then it throws an exception which is handled with an “exception occurs” message and then returns 0 to the main() method.
Now the value of the user defined method firstuppercase() is stored in an integer variable say ‘b’ inside the main() method.
Print the value of first uppercase in that string.

Program:

import java.util.*;
import java.io.*;
public class Main 
{
    public static void main(String[] args)
    {
        //declare and initialize an String variable str
        String str = "i LoVe JaVa";
        System.out.println("The string is: "+str);
        //define the method and store the first uppercase value inside an integer variable say ‘b’
        char b = firstuppercase(str,0);
        //print the result
        if (b == 0)
            System.out.println("The string has No uppercase letter");
        else
             System.out.println("The first uppercase in the string is: "+b);
    }
    
    // firstuppercase() function is called to find the first uppercase in the string
    static char firstuppercase(String str, int n)
    {
        // checking if the 1st character is uppercase or not
        if(Character.isUpperCase(str.charAt(n))) 
        {
            return str.charAt(n);
        }
        //calling firstuppercase() function recursively to find the first uppercase in the string
        try 
        {
            return firstuppercase(str, n + 1);
        }
        // if there is no uppercase letter in the string then it throws an exception and return 0
        catch(Exception e)
        {
            System.out.println("Exception occurs ");
        }
        return 0;
    }
}

Output:

The string is: i LoVe JaVa
The first uppercase in the string is: L

Method-2: Java Program to Find First Uppercase Letter in a String By Using User Input and Recursion

Approach:

Create a scanner class.
Declare a string variables say ‘str’
Prompt the user to enter the values for the string.
Call a user defined method firstuppercase() and pass the string ‘str’ and the 1^st index ‘0’ as parameter.
Inside the user defined method we will check if the 1st character is uppercase or not.
If the 1^st char is uppercase then return that value else call the firstuppercase() method recursively to find the first uppercase value.
If the string has no uppercase value then it throws an exception which is handled with an “exception occurs” message and then returns 0 to the main() method.
Now the value of the user defined method firstuppercase() is stored in an integer variable say ‘b’ inside the main() method.
Print the value of first uppercase in that string.

Program:

import java.util.*;
import java.io.*;
public class Main 
{
    public static void main(String[] args)
    {
        // create a scanner class
        Scanner s = new Scanner(System.in);
        System.out.println("Enter a string value: ");
        //declare an integer variable ‘n’and initialize it by user input using scanner class.
        String str = s.nextLine();
        System.out.println("The string is: "+str);
        //define the method and store the first uppercase value inside an integer variable say ‘b’
        char b = firstuppercase(str,0);
        //print the result
        if (b == 0)
            System.out.println("The string has No uppercase letter");
        else
            System.out.println("The first uppercase in the string is: "+b);
    }
    
    // firstuppercase() function is called to find the first uppercase in the string
    static char firstuppercase(String str, int n)
    {
        // checking if the 1st character is uppercase or not
        if(Character.isUpperCase(str.charAt(n))) 
        {
            return str.charAt(n);
        }
        //calling firstuppercase() function recursively to find the first uppercase in the string
        try 
        {
            return firstuppercase(str, n + 1);
        }
        // if there is no uppercase letter in the string then it throws an exception and return 0
        catch(Exception e)
        {
            System.out.println("Exception occurs ");
        }
        return 0;
    }
}

Output:

Enter a string value: 
btechgeeks
The string is: btechgeeks
Exception occurs 
The string has No uppercase letter

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