Static Methods

A static method is hidden, not overridden when a subclass defines a static method with the same name.

class Animal {
    static void test() {
        System.out.println("Animal");
    }

    void show() {
        System.out.println("Animal instance");
    }
}

class Cat extends Animal {
    static void test() {
        System.out.println("Cat");
    }

    @Override
    void show() {
        System.out.println("Cat instance");
    }
}

Cat cat = new Cat();
Animal animal = cat;

Animal.test();  // Animal
animal.show();  // Cat instance

Remember:

static method → hidden → depends on reference/class type
instance method → overridden → depends on actual object

Interface Methods

Interfaces can have default methods with implementations.

interface Flyer {
    default void show() {
        System.out.println("I can fly");
    }
}

interface Swimmer {
    default void show() {
        System.out.println("I can swim");
    }
}

If a class implements both, Java doesn't know which show() to use.

class Duck implements Flyer, Swimmer {

    @Override
    public void show() {
        Flyer.super.show();
    }
}

Now:

Duck duck = new Duck();
duck.show();

Output:

I can fly

Important Rules

1. Class method wins over interface default method.

class Animal {
    void show() {
        System.out.println("Animal");
    }
}

interface Flyer {
    default void show() {
        System.out.println("Flyer");
    }
}

class Bird extends Animal implements Flyer {
}

Animal.show() is used.

2. Two interfaces with the same default method → class must override it.

class Duck implements Flyer, Swimmer {

    @Override
    public void show() {
        Flyer.super.show();
    }
}

You can choose an interface's default method using:

Flyer.super.show();

3. Static methods in interfaces are NOT inherited.

interface Animal {
    static void test() {
        System.out.println("Animal");
    }
}

Call it using:

Animal.test();

Not:

someObject.test(); // ERROR

Easy Summary

Static methods → hidden, not overridden.
Instance methods → overridden.
Class method beats interface default method.
Conflicting interface defaults → subclass must override.
Interface static methods → not inherited.