Object Oriented Programming Through Java

Answer:

Key Features of Java:

Java is a popular, high-level, object-oriented programming language developed by Sun Microsystems (now owned by Oracle). It provides several important features that make it powerful and widely used.

1. Simple:

Java is easy to learn and use because it removes complex features like pointers, operator overloading, and multiple inheritance.

2. Object-Oriented:

Everything in Java is treated as an object. It supports OOP concepts such as inheritance, encapsulation, polymorphism, and abstraction.

3. Platform Independent:

Java code can run on any platform (Windows, Mac, Linux, etc.) without modification, thanks to the Java Virtual Machine (JVM).

4. Secure:

Java provides a secure environment through features like bytecode verification, sandboxing, and absence of explicit pointers.

5. Robust:

Java handles errors effectively with exception handling and has strong memory management using automatic garbage collection.

6. Multithreaded:

Java allows the execution of multiple threads (lightweight processes) simultaneously, improving performance.

7. Portable:

Java programs are portable because the same .class file can run anywhere a JVM is installed.

8. High Performance (with JIT):

The Just-In-Time (JIT) compiler improves performance by converting bytecode into native machine code at runtime.

Answer:

→ Constructor is like a special method used in object creation & most importantly to initialise non-static properties during the object creation.

→ The name of the constructor would be always similar to class name & it do not contain any return type.

→ We can't create Java program without the constructors. Since compiler automatically adds the constructor if the developer forgets to add it.

Syntax:

[Access Specifier] ClassName(F.A's)
{
    // statements
}

Types of Constructors:

→ We have three types of constructors.

1. Default Constructor:

 Whenever developer creates a class without constructor, compiler mandatory/compulsarily adds the constructor without formal arguments known as default constructor.

2. Non-Argument Constructor:

If a developer add constructor without formal arguments known as Non-Argument constructor

Ex: A obj = new A();

3. Parameterized Constructor:

A constructor add by developer with formal arguments known as Parameterized constructor which is

mainly used to initialized non static properties during the object creation

Example:

U.L

A obj 1 = new (10,20);

B.P

A(int a, int b){
    This.a=a;
    This.b=b;
}

Answer:

Inheritance

It is similar to parent & child relationship where non-static properties & behaviour of an parent class/superclass are acquired by sub class object by using extends keyword btw the classes called as Inheritance.

Child class (or) Sub class

A child which acquires another class properties & behaviour is known as sub class /child class.

Parent class (or) super class

A class which provide the property & behaviour to another class is known as parent class/ super class

Only non-static properties & behaviour are inherited to sub class

Types of inheritance

There are 5 types of inheritance in java, they are

• Single level inheritance
• Multi-level inheritance
• Multiple inheritance
• Hierarchical inheritance
• Hybrid inheritance

1. Single level inheritance: A subclass inherits from only one superclass.

2. Multi-level inheritance:

Inheritance with respect to more than one level is known M-LI

3. Multiple inheritance:

one sub class having multiple super class in a same level is known as m-ln

4. Hierarchical inheritance:

one super class having multiple sub class in a same level is known as hierarchical inheritance

5. Hybrid inheritance:

combination of any two types of inheritance is known as hybrid inheritance.

Answer:

In Java, a package is a collection of related classes, interfaces, and sub-packages that are grouped together to avoid name conflicts and to organize files properly. It acts as a namespace that helps to categorize classes logically (like folders in a computer).

Example:

package mypackage;

public class Example {
    public void display() {
        System.out.println("This is a package example");
    }
}

Types of Packages:

1. Built-in Packages (Predefined Packages):

These are packages provided by Java itself.

Answer:

Key Features of Java:

Java is a popular, high-level, object-oriented programming language developed by Sun Microsystems (now owned by Oracle). It provides several important features that make it powerful and widely used.

1. Simple:

Java is easy to learn and use because it removes complex features like pointers, operator overloading, and multiple inheritance.

2. Object-Oriented:

Everything in Java is treated as an object. It supports OOP concepts such as inheritance, encapsulation, polymorphism, and abstraction.

3. Platform Independent:

Java code can run on any platform (Windows, Mac, Linux, etc.) without modification, thanks to the Java Virtual Machine (JVM).

4. Secure:

Java provides a secure environment through features like bytecode verification, sandboxing, and absence of explicit pointers.

5. Robust:

Java handles errors effectively with exception handling and has strong memory management using automatic garbage collection.

6. Multithreaded:

Java allows the execution of multiple threads (lightweight processes) simultaneously, improving performance.

7. Portable:

Java programs are portable because the same .class file can run anywhere a JVM is installed.

8. High Performance (with JIT):

The Just-In-Time (JIT) compiler improves performance by converting bytecode into native machine code at runtime.

ANSWER:

a.The new keyword in java is a crucial operator primarily used for object creation and dynamic memory allocation.It performs several key functions

Example:

Student s=new student();

b.Yes,in java a class can extend multiple interfaces,allowing multiple inheritance of type.

Example:

class demo implements A,B{ }

c.An exeption in java is an unwanted event or error thsat occurs during program execution,distrupting the normal flow of instructions.