Inheritance (Extending a Class)

This lesson covers extending a class through inheritance in Java, so classes with a shared trait can reuse code. It's for anyone searching "Java inheritance usage."

Inherit with extends. Add @Override to override a parent's method. Bundling shared parts into a parent class saves you from writing the same code repeatedly.

The example has Dog inherit Animal with extends Animal, and override the parent's method with @Override. It's a classic technique — building on a shared "animal" blueprint, then adding a specific sound for "dog."

A common early mistake is forgetting the @Override annotation. The code often still works without it, but including it makes typos and similar mistakes easier to catch at compile time.

In real projects, overusing inheritance can make relationships between classes overly complex, so balancing your design matters.

📖 Reference code

class Animal {
    String name;
    Animal(String name) { this.name = name; }
    String speak() { return name + " makes a sound"; }
}

class Dog extends Animal {
    Dog(String name) { super(name); }
    @Override
    String speak() { return name + " says \"Woof\""; }
}

Dog dog = new Dog("Rex");
System.out.println(dog.speak());

✍️ Your code

Type your code, then press "Run"

🧪 This site can't compile or run Java directly, so it checks on the spot whether what you typed matches the reference code (scoring happens entirely in your browser — nothing is sent anywhere).