Java Random Number Generate Program? Can you specifically explain -->> otp[i] = numbers.charAt(rndm_method.nextInt(numbers.length())) [closed]

//Program to generate random numbers for OTP(One Time Password). // How you can generate a random number with specific range

public class OtpGenerate {

    public static char[] OTP(int len) {
        System.out.println("Generating OTP using random() : ");
        System.out.print("You OTP is : ");

        // Using numeric values
        String numbers = "0123456789";

        // Using random method
        Random rndm_method = new Random();

        char[] otp = new char[len];

        for (int i = 0; i < len; i++) {
            // Use of charAt() method : to get character value
            // Use of nextInt() as it is scanning the value as int
            **otp[i] = numbers.charAt(rndm_method.nextInt(numbers.length()));**
        }
        return otp;
    }

}