How can multiple inheritance be emulated in object-oriented languages?.

In Java, multiple inheritance of classes is not directly supported, but it can be emulated using interfaces and composition.

1. Interfaces — a class can implement multiple interfaces, allowing it to "inherit" behavior from multiple sources.

2. Composition — a class contains objects of other classes and delegates method calls to them, thus combining functionality.

Example with interfaces:

interface Flyable {
    void fly();
}

interface Swimmable {
    void swim();
}

class Duck implements Flyable, Swimmable {
    public void fly() {
        System.out.println("Duck is flying");
    }
    public void swim() {
        System.out.println("Duck is swimming");
    }
}

Example with composition:

class Engine {
    void start() { System.out.println("Engine started"); }
}

class Car {
    private Engine engine = new Engine();
    void start() {
        engine.start();
        System.out.println("Car is moving");
    }
}