From how many classes can a class in Java inherit?

In Java, a class can directly inherit from only one parent class. This is a feature of single inheritance.

Example:

// Parent class
class Animal {
    // methods and fields
}

// Child class, inherits from Animal
class Dog extends Animal {
    // methods and fields
}

// It is not allowed in Java to inherit from multiple classes simultaneously
// class Cat extends Animal, Pet { // Compilation error
//     // methods and fields
// }

However, a class can implement multiple interfaces.

// Interface 1
interface Swimmer {
    void swim();
}

// Interface 2
interface Runner {
    void run();
}

// A class can implement multiple interfaces
class Duck implements Swimmer, Runner {
    @Override
    public void swim() {
        // implementation of swimming
    }

    @Override
    public void run() {
        // implementation of running
    }
}