Error: no suitable method found for length(int) - string

Question

First time posting a question. Maybe I'm just being an idiot that's not seeing the problem, but can anyone identify what's wrong with my code below? Everything else works fine. But when the code is done compiling, it says "Error: no suitable method found for length(int)" for if (l.length(0)) and if (f.length(0)).
import java.util.Scanner;
public class Project2 {
public static void main(String[] args) {
Scanner scnr = new Scanner(System.in);
int salary;
double savingsRate;
double interestRate;
int employmentYears;
double retirementSavings;
System.out.println("Enter input salary savings_rate interest_rate years_employed lastname firstname");
salary = scnr.nextInt();
savingsRate = scnr.nextDouble();
interestRate = scnr.nextDouble();
employmentYears = scnr.nextInt();
String l = scnr.nextLine(); // Last Name
String f = scnr.nextLine(); // First Name
retirementSavings = employmentYears * savingsRate * salary * (1 + interestRate);
if (salary < 0) {
System.out.println("Salary is negative");
}
else if (salary > 1000000) {
System.out.println("Error: Salary " + salary + "exceeds maximum 1000000.0");
}
else {
System.out.println("Salary: " + salary);
}
if (savingsRate < 0) {
System.out.println("Savings rate is negative");
}
else if (savingsRate > 0.5) {
System.out.println("Error: Savings rate " + savingsRate + "exceeds maximum 0.5");
}
else {
System.out.println("Savings Rate:" + savingsRate);
}
if (interestRate < 0) {
System.out.println("Interest Rate is negative");
}
else if (interestRate > 0.25) {
System.out.println("Error: Interest Rate " + interestRate + "exceeds maximum 0.25");
}
else {
System.out.println("Interest Rate: " + interestRate);
}
if (employmentYears < 0) {
System.out.println("Years employed is negative!");
}
else if (employmentYears > 50) {
System.out.println("Error: Years employed " + employmentYears + "exceeds maximum 50");
}
else {
System.out.println("Years of Employment: " + employmentYears);
}
if (l.length(0)) {
System.out.println("Error: Name too short");
}
else if (l == f) {
System.out.println("Error: Last Name and First Name are the same");
}
else {
System.out.println("Last Name: " + l);
}
if (f.length(0)) {
System.out.println("Error: Name too short");
}
else {
System.out.println("First Name: " + f);
}
System.out.println("Retirement Savings: " + retirementSavings);
}
}

Answer 1

I think you are trying to check if the name is empty, Am I right?
you have:
1) string.length() : length() method is a final variable which is applicable for string objects. length() method returns the number of characters presents in the string.
2) array.length : length is a final variable applicable for arrays. With the help of length variable, we can obtain the size of the array.
(visit geeksforgeeks to see more).
But you don't have a String.length(int) method.