Length of the string without using length() function in Java

Understanding String Length Calculation

The length of a string is the number of characters it contains. In Java, we can determine this without using the built-in length() function.

We will explore three different methods to find the length of a string in Java.

Method 1: Using a Loop

This method uses a loop to count the characters in the string.

import java.util.Scanner;

public class StringLengthLoop {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter a string: ");
        String str = scanner.nextLine();
        scanner.close();
        
        int length = 0;
        for (char ch : str.toCharArray()) {
            length++;
        }
        
        System.out.println("Length of the string is " + length);
    }
}
            

Method 2: Using Recursion

This method calculates the length of the string recursively.

import java.util.Scanner;

public class StringLengthRecursion {
    public static int findLength(String str, int index) {
        if (index >= str.length())
            return index;
        return findLength(str, index + 1);
    }
    
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter a string: ");
        String str = scanner.nextLine();
        scanner.close();
        
        System.out.println("Length of the string is " + findLength(str, 0));
    }
}
            

Method 3: Using Character Array

This method converts the string to a character array and counts its elements.

import java.util.Scanner;

public class StringLengthArray {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter a string: ");
        String str = scanner.nextLine();
        scanner.close();
        
        char[] charArray = str.toCharArray();
        int length = 0;
        for (char c : charArray) {
            length++;
        }
        
        System.out.println("Length of the string is " + length);
    }
}