Override rules
- Java course
- Intermediate
- Lesson 61/116
- 5 min
Learn @Override and its rules.
Override and @Override
When you override a method, adding the @Override annotation is a good habit. It tells the compiler "I intend to override this method." If the signature has a typo, you get a compile error; this catches silent bugs.
Do not confuse override with overload. Overload defines a new method with the same name but a different parameter list; it does not use dynamic dispatch. Override replaces the parent method.
Calling the parent with super
Sometimes you want to call the parent version of a method you overrode. super.method() does that. For instance super.area() runs the parent's area method; you can use its result inside the child method.
This is especially useful in the template method pattern: the parent provides an algorithm skeleton, and subclasses customize some steps while keeping the skeleton via super.
Practice Use override + super to build a sound
Define class Animal with a String sound() { return ""; } method. Define class Dog extends Animal that overrides sound with @Override and returns super.sound() + "Woof";. In main, assign with Animal a = new Dog(); and print System.out.println(a.sound());.
Starter code
// Define the Animal class: sound returns the empty string
// Dog extends Animal; the sound method is overridden
// main: assign a Dog instance as Animal and printSample solution
class Animal {
String sound() { return ""; }
}
class Dog extends Animal {
@Override
String sound() { return super.sound() + "Woof"; }
}
public class Main {
public static void main(String[] args) {
Animal a = new Dog();
System.out.println(a.sound());
}
}Expected output
Woof
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Which of the following is NOT override?
- A subclass method marked @Override with matching signature
- Widening a protected parent method to public
- A new method with the same name but different parameters Correct answer
- Implementing an abstract method in a concrete subclass
Explanation: Same name with different parameters is overload, not override.
2 Add the override annotation
class Dog extends Animal {
____
String sound() { return "Woof"; }
}class Dog extends Animal {
@Override
String sound() { return "Woof"; }
}Explanation: @Override tells the compiler this method overrides the parent.
3 Match the override and overload concepts
| Term | Meaning |
|---|---|
@Override |
Marks override intent |
overload |
Same name, different parameters |
super.method() |
Calls the parent method |
final |
Blocks override |