Calling a method inside another method in same class

In page 428 (the chapter about Type Information) of his "Thinking In Java, 4th Ed.", Bruce Eckel has the following example:

public class Staff extends ArrayLis开发者_开发百科t<Position> {
    public void add(String title, Person person) {
        add(new Position(title, person));
    }
/* rest of code snipped */

Maybe I'm a bit tired, but I can't see how the call to add() inside the add() method works. I keep thinking that it should have a reference, or be a static method (and I can't find a static add() in ArrayList or List). What am I missing?

I just tested for myself, and found that this works:

// Test2.java
public class Test2 {
    public void testMethod() {
        testMethod2();
    }

    public void testMethod2() {
        System.out.println("Here");
    }

    public static void main(String[] args) {
        Test2 t = new Test2();
        t.testMethod();
    }
}

Java implicitly assumes a reference to the current object for methods called like this. So

// Test2.java
public class Test2 {
    public void testMethod() {
        testMethod2();
    }

    // ...
}

Is exactly the same as

// Test2.java
public class Test2 {
    public void testMethod() {
        this.testMethod2();
    }

    // ...
}

I prefer the second version to make more clear what you want to do.

It is not recursion, it is overloading. The two add methods (the one in your snippet, and the one "provided" by ArrayList that you are extending) are not the same method, cause they are declared with different parameters.

The add method that takes a String and a Person is calling a different add method that takes a Position. The one that takes Position is inherited from the ArrayList class.

Since your class Staff extends ArrayList<Position>, it automatically has the add(Position) method. The new add(String, Person) method is one that was written particularly for the Staff class.

It is just an overload. The add method is from the ArrayList class. Look that Staff inherits from it.

Recursion is a method that call itself. In this case it is a recursion. However it will be overloading until you put a restriction inside the method to stop the loop (if-condition).