Java Programming Concepts

What is method overloading in Java?

• Method overloading is when a method can be overridden in a subclass.

• Method overloading is the ability to change the return type of a method without changing its parameters.

• Method overloading is the ability to define multiple methods with the same name but different parameter lists in a class.

• Method overloading requires methods to have different names.

Provide an example of method overloading in Java.

• class MathOperations { double add(int a, double b) { return a + b; } }

• class MathOperations { void add(int a, int b) {} }

• Example of method overloading: class MathOperations { // Method to add two integers int add(int a, int b) { return a + b; } // Method to add three integers int add(int a, int b, int c) { return a + b + c; } // Method to add two double values double add(double a, double b) { return a + b; } }

• class MathOperations { int add(int a) { return a; } }

How does method overloading differ from method overriding?

• Method overloading requires different method names; method overriding does not.

• Method overloading is about having the same method name with different signatures; method overriding is about redefining a method in a subclass.

• Method overloading is used for private methods only; method overriding is for public methods.

• Method overloading changes the return type; method overriding changes the access modifier.

What is the purpose of the @Override annotation?

• To define a new method in a subclass.

• To indicate a method is private.

• To indicate that a method overrides a method in a superclass.

• To mark a method as deprecated.

When should you use the @Override annotation?

• Use @Override when a method is overriding a method from a superclass.

• Use @Override when creating new methods.

• Use @Override for private methods only.

• Use @Override to indicate a method is final.

Explain call by value in Java.

• Call by value in Java is the same as call by reference in other programming languages.

• Call by value in Java allows methods to modify the original object directly.

• Call by value in Java means passing the original variable itself to methods.

• Call by value in Java means passing a copy of the variable's value to methods, affecting primitives and object references differently.

Explain call by reference in Java.

• Java uses 'call by reference' for all data types.

• Java passes object references by value, preventing any changes to the object.

• Java uses 'call by value', but when passing objects, the reference to the object is copied, allowing modifications to the object's state.

• Passing primitives in Java allows direct modification of their values.

What is polymorphism in programming?

• Polymorphism refers to the process of compiling code into machine language.

• Polymorphism is the ability to create multiple instances of a class.

• Polymorphism is the ability of different classes to be treated as instances of the same class through a common interface.

• Polymorphism is a method of optimizing memory usage in programming.

How can you demonstrate polymorphism using method overriding?

• Create a base class 'Animal' with a method 'speak'. Override 'speak' in derived classes 'Dog' and 'Cat'. Call 'speak' on an 'Animal' reference pointing to 'Dog' or 'Cat' to demonstrate polymorphism.

• Create a base class 'Animal' with a method 'sleep'. Override 'sleep' in derived classes 'Dog' and 'Cat' and call 'sleep' on 'Animal' reference.

• Create a class 'Animal' with a method 'run'. Override 'run' in derived classes 'Dog' and 'Cat'.

• Define a base class 'Animal' with a method 'eat'. Call 'eat' on an 'Animal' reference.

Write a simple program that shows method overriding.

• class Dog extends Animal { }

• class Animal { sound() { return 'Some sound'; } } class Dog extends Animal { sound() { return 'Bark'; } } const myDog = new Dog(); console.log(myDog.sound()); // Output: Bark

• const myDog = new Animal(); console.log(myDog.sound());

• class Animal { bark() { return 'Bark'; } }