Testing equality of objects in Java with equals method

Question

I want to ask a question about using the equals method to test object equality in Java.

I am a beginner in Java and currently progressing through the Dummies Java 9-in-1 book.

I have written the following code to check the equality of two Employee objects:

public class TestEquality2 {
    public static void main (String [] args) {
        Employee emp1 = new Employee ("Martinez", "Anthony");
        Employee emp2 = new Employee ("Martinez", "Anthony");
        if (emp1.equals(emp2))
            System.out.println("These employees are the same");
        else
            System.out.println("These employees are different.");
    }
}

class Employee {
    private String firstName;
    private String lastName;

    public Employee (String firstName, String lastName) {
        this.lastName = lastName;
        this.firstName = firstName;
    }

    public String getLastName() {
        return this.lastName;
    }

    public String getFirstName() {
        return this.firstName;
    }

    public boolean equals (Object obj) {
        // an object must equal itself
        if (this == obj)
            return true;

        // no object equals null
        if (this == null)
            return false;

        if (this.getClass() != obj.getClass())
            return false;

        // Cast to an employee, then compare the fields
        Employee emp = (Employee) obj;
        // is this the string's equals method?
        return this.lastName.equals(emp.getLastName()) && this.firstName.equals(emp.getFirstName());
    }
}

The line of concern is the last one of the equals(Object obj) method.

As per the code, I have overriden the default Object equals () method and supplied my own design, but I was confused here:

return this.lastName.equals(emp.getLastName()) && this.firstName.equals(emp.getFirstName());

I know that lastName is a string, but the equals() method that I am using here, is this the equals() method for a String or the one I've just defined? If it's the latter, I know that I would create a recursive situation, although I'm confident I am using the String equals() yet I want to clarify for completion.

Answer 1

lastName is a String, so calling this.lastName.equals(emp.getLastName()) will use String's implementation of the equals method. The same goes for the comparison of the first names, of course.