Populating Properties In Object Class Using A Loop

I am parsing an XML file. i.e.

<people>
     <person  firstname="John" lastname="Doe"  age="50" />
     <person  firstname="Thomas" lastname="Jefferson" age="260" />
<people>
 
I have created Person.java with the following attributes:
 
private String firstName;
private String lastName;
private int age;
 
My main method parses the XML, loops through each person, and gets the attributes for each.
 
I need to create instances of my Person class. I could write something like this:
 
Person person = new Person();
for (int i = 0; i < attributes.getLength; i++) {
  if (attribute.getName(i) = "firstname") { person.firstName = attribute.getValue(i);}
  if (attribute.getName(i) = "lastname") { person.lastName = attribute.getValue(i); }
  if (attribute.getName(i) = "age") { person.age = attribute.getValue(i); }
}
 
Since my actual XML has quite a few attributes, I would rather do something like this:
 
Person person = new Person();
for (int i = 0; i < attributes.getLength(); i++) {
  person[attribute.getName(i)] = attribute.getValue(i);
}
 
This doesn't work.