title: My method from another class, will not call an input in my Main class
body: <p>I'm teaching myself Java, and I'm trying to run a piece of code I made. I am at the point in my Udemy Self learning course where we are talking about classes. I made a project in my IDE IntelliJ, called Person. Essentially the goal is to input a first and last name as a string, and an age as a number, it then runs through and spits out the persons full name and if they are a teenager.</p>
  
  <p>I however am at the input stage, and I keep getting an error message in my Main Class. When I try to input Dan however, (person.SetFirstName("Dan")), it comes back with an error saying, "setFirstName() in person cannot be applied to java.lang.String"</p>
  
  <p>Below you'll find my code from the main class, and the first few lines of my person class, I feel like if I can figure out the issue with the first method, I can fix the rest. </p>
  
  <p>I've asked in my class forum, but I can't seem to get an answer, some people think that it might be an issue with my IDE itself? </p>
  
  <p>public class Main {</p>
  
  <pre><code>public static void main(String[] args) {
  
  Person person = new Person();
  person.setFirstName("Dan");
  person.setLastName();
  person.setAge();
      System.out.println("Full Name = " + person.getFullName());
      System.out.println("Are they a teenager? " + person.isTeen());
      person.setFirstName();
      person.setAge();
      System.out.println("Full Name = " + person.getFullName());
      System.out.println("Are they a teenager? " +person.isTeen());
      person.setLastName();
      System.out.println("Full Name = " + person.getFullName());
  
  }
  </code></pre>
  
  <p>}</p>
  
  <p>public class Person {</p>
  
  <pre><code>private String firstName;
  private String lastName;
  private int age;
  
  public String getFirstName(){
      return this.firstName;
  }
  public void setFirstName(){
      this.firstName = firstName;
  }
  </code></pre>