Welcome back! In this lesson, we're going to explore a critical area of inheritance in Java: overriding methods and attributes. It's akin to taking a classic recipe, the parent class, and tweaking it to suit your unique taste, the child class. Let's begin!

Inheritance in Java allows a class, referred to as a child, to 'inherit' properties and behaviors from another class, the parent. This is achieved using the keyword extends.

public class Smartphone extends CellPhone {}

In this example, Smartphone inherits all aspects of CellPhone.

Overriding enables a child class to customize inherited methods. When a child class declares a method that is already present in the parent class, we refer to this as method overriding.

Here's an example of how Smartphone overrides a method in CellPhone:

public class CellPhone {
    // A method in parent class
    public void displayBatteryStatus() {
        System.out.println("Battery status displayed with an icon.");
    }
}

public class Smartphone extends CellPhone {
    // Method overridden in child class
    @Override
    public void displayBatteryStatus() {
        System.out.println("Battery status displayed as a percentage.");
    }
}

In this case, Smartphone overrides the displayBatteryStatus method to implement a unique action.

Child classes can also override inherited attributes. For instance, CellPhone possesses an attribute named hasTouchScreen, which is set to false. In contrast, Smartphone changes this attribute as it does feature a touchscreen.

public class CellPhone {
    // An attribute in the parent class
    public boolean hasTouchScreen = false;
}

public class Smartphone extends CellPhone {
    // The same attribute overridden in the child class
    public boolean hasTouchScreen = true;
}

Here, Smartphone overrides the hasTouchScreen attribute to reflect its unique capabilities accurately.

The protected identifier in Java serves as a mid-point between private and public. When marked protected, an attribute becomes accessible within all subclasses.

public class CellPhone {
    // Protected attribute in parent class
    protected boolean hasPhysicalKeypad = true;
}

public class Smartphone extends CellPhone {
    // The protected attribute overridden in the child class
    protected boolean hasPhysicalKeypad = false;
}

CellPhone phone = new CellPhone();
System.out.println(phone.hasPhysicalKeypad); // Error! Can't directly access protected field

In this scenario, Smartphone is allowed to access and override the protected attribute hasPhysicalKeypad. At the same time, just directly accessing the same field, or accessing it from a non-inherited class, doesn't work.