Bharat Singh

Software Engineering

[Bharat Singh @Bharatastic]

Most Java developers use Java every day —
But very few truly understand it.

[Bharat Singh @Bharatastic]

𝗜𝗻 𝘀𝗶𝗺𝗽𝗹𝗲 𝘁𝗲𝗿𝗺𝘀:
• Overloading → multiple ways to call a method
• Overriding → changing behavior in subclasses

Understanding this difference is essential

𝘿𝙤 𝙔𝙤𝙪 𝙍𝙚𝙖𝙡𝙡𝙮 𝙆𝙣𝙤𝙬 𝙅𝙖𝙫𝙖? — 𝙋𝙖𝙧𝙩 35

#Java #SoftwareEngineering

[Bharat Singh @Bharatastic]

𝗠𝗲𝘁𝗵𝗼𝗱 𝗼𝘃𝗲𝗿𝗹𝗼𝗮𝗱𝗶𝗻𝗴 𝘃𝘀 𝗺𝗲𝘁𝗵𝗼𝗱 𝗼𝘃𝗲𝗿𝗿𝗶𝗱𝗶𝗻𝗴 - 𝗗𝗼 𝘆𝗼𝘂 𝗸𝗻𝗼𝘄 𝘁𝗵𝗲 𝗿𝗲𝗮𝗹 𝗱𝗶𝗳𝗳𝗲𝗿𝗲𝗻𝗰𝗲?

Both are forms of polymorphism in Java -
but they solve very different problems.

[Bharat Singh @Bharatastic]

𝗠𝗲𝘁𝗵𝗼𝗱 𝗼𝘃𝗲𝗿𝗹𝗼𝗮𝗱𝗶𝗻𝗴
• Same method name, different parameters
• Happens in the same class
• Resolved at compile time

𝗠𝗲𝘁𝗵𝗼𝗱 𝗼𝘃𝗲𝗿𝗿𝗶𝗱𝗶𝗻𝗴
• Same method signature in parent and child class
• Enables runtime behavior changes
• Resolved at runtime

[Bharat Singh @Bharatastic]

Inheritance enables reuse and polymorphism,
Inheritance also introduces 𝘁𝗶𝗴𝗵𝘁 𝗰𝗼𝘂𝗽𝗹𝗶𝗻𝗴.

Use inheritance intentionally.
Prefer composition when possible.

𝘿𝙤 𝙔𝙤𝙪 𝙍𝙚𝙖𝙡𝙡𝙮 𝙆𝙣𝙤𝙬 𝙅𝙖𝙫𝙖? — 𝙋𝙖𝙧𝙩 34

#Java #SoftwareEngineering

[Bharat Singh @Bharatastic]

𝗜𝗻𝗵𝗲𝗿𝗶𝘁𝗮𝗻𝗰𝗲 - 𝗣𝗼𝘄𝗲𝗿 𝗮𝗻𝗱 𝗗𝗮𝗻𝗴𝗲𝗿

Inheritance lets a class derive 𝗮𝘁𝘁𝗿𝗶𝗯𝘂𝘁𝗲𝘀 𝗮𝗻𝗱 𝗯𝗲𝗵𝗮𝘃𝗶𝗼𝗿𝘀 from another class.

It enables you to create new classes from existing ones, thereby improving code reuse and structure.

[Bharat Singh @Bharatastic]

• A child class can directly use the parent class’s variables and methods without duplicating code.
• A child class can also introduce new features or override existing ones to enhance functionality.

It provides:
• Code reuse
• Polymorphism
• Clear “is-a” relationships

[Bharat Singh @Bharatastic]

Constructor Overloading adds flexibility,
But too many constructors hurt readability.

𝘿𝙤 𝙔𝙤𝙪 𝙍𝙚𝙖𝙡𝙡𝙮 𝙆𝙣𝙤𝙬 𝙅𝙖𝙫𝙖? — 𝙋𝙖𝙧𝙩 33

#Java #SoftwareEngineering

[Bharat Singh @Bharatastic]

𝗖𝗼𝗻𝘀𝘁𝗿𝘂𝗰𝘁𝗼𝗿 𝗼𝘃𝗲𝗿𝗹𝗼𝗮𝗱𝗶𝗻𝗴 -
𝗺𝘂𝗹𝘁𝗶𝗽𝗹𝗲 𝘄𝗮𝘆𝘀 𝘁𝗼 𝗰𝗿𝗲𝗮𝘁𝗲 𝗮𝗻 𝗼𝗯𝗷𝗲𝗰𝘁.

Defining more than one constructor inside a class is 𝗖𝗼𝗻𝘀𝘁𝗿𝘂𝗰𝘁𝗼𝗿 𝗢𝘃𝗲𝗿𝗹𝗼𝗮𝗱𝗶𝗻𝗴.

The 𝘀𝗶𝗴𝗻𝗮𝘁𝘂𝗿𝗲 of the constructor must be different.

[Bharat Singh @Bharatastic]

We can change the signature of the constructor in the following ways:

  • By changing the 𝗻𝘂𝗺𝗯𝗲𝗿 𝗼𝗳 𝗽𝗮𝗿𝗮𝗺𝗲𝘁𝗲𝗿𝘀.
  • By changing the 𝗱𝗮𝘁𝗮𝘁𝘆𝗽𝗲𝘀 𝗼𝗳 𝗮𝗿𝗴𝘂𝗺𝗲𝗻𝘁𝘀.
  • By changing the 𝘀𝗲𝗾𝘂𝗲𝗻𝗰𝗲 𝗼𝗳 𝗮𝗿𝗴𝘂𝗺𝗲𝗻𝘁𝘀.

[Bharat Singh @Bharatastic]

Why this matters:

Good constructors = clean objects.
Bad constructors = bugs waiting to happen.

They don’t just create objects,
They define object quality.

𝘿𝙤 𝙔𝙤𝙪 𝙍𝙚𝙖𝙡𝙡𝙮 𝙆𝙣𝙤𝙬 𝙅𝙖𝙫𝙖? — 𝙋𝙖𝙧𝙩 32.1

#Java #OOP #SoftwareEngineering

[Bharat Singh @Bharatastic]

𝗧𝘆𝗽𝗲𝘀 𝗼𝗳 𝗖𝗼𝗻𝘀𝘁𝗿𝘂𝗰𝘁𝗼𝗿𝘀 𝗶𝗻 𝗝𝗮𝘃𝗮 - 𝘄𝗵𝗮𝘁 𝗮𝗿𝗲 𝘁𝗵𝗲𝘆 𝗿𝗲𝗮𝗹𝗹𝘆?

In Java, constructors aren’t just about creating objects.
They control how objects are born.

There are several types of constructors:

[Bharat Singh @Bharatastic]

𝗖𝗼𝗽𝘆 𝗖𝗼𝗻𝘀𝘁𝗿𝘂𝗰𝘁𝗼𝗿
• Creates a new object using another object
• Java doesn’t provide it by default - you define it
• Useful for cloning state

[Bharat Singh @Bharatastic]

Constructors enforce:

• Proper initialization
• Required dependencies
• Controlled object creation

They’re not just syntax -
They define how objects come into existence.

𝘿𝙤 𝙔𝙤𝙪 𝙍𝙚𝙖𝙡𝙡𝙮 𝙆𝙣𝙤𝙬 𝙅𝙖𝙫𝙖? — 𝙋𝙖𝙧𝙩 32

#Java #SoftwareEngineering

[Bharat Singh @Bharatastic]

𝗖𝗼𝗻𝘀𝘁𝗿𝘂𝗰𝘁𝗼𝗿𝘀 - 𝘄𝗵𝘆 𝘁𝗵𝗲𝘆 𝗿𝗲𝗮𝗹𝗹𝘆 𝗺𝗮𝘁𝘁𝗲𝗿 𝗶𝗻 𝗝𝗮𝘃𝗮.

A constructor looks like a method, but it’s not.

When you write:
new MyClass()

The constructor runs to bring an object to life.
Without constructors, objects could start broken or incomplete.

[Bharat Singh @Bharatastic]

What constructors do:

• Allocate memory
• Initialize instance variables
• Ensure valid object state
• No return type allowed
• Same name as class + ()
• Creating the object = running the constructor

They control how objects are born.

[Bharat Singh @Bharatastic]

You write classes.
You work with objects.

Understanding this distinction is fundamental to object-oriented thinking.

𝘿𝙤 𝙔𝙤𝙪 𝙍𝙚𝙖𝙡𝙡𝙮 𝙆𝙣𝙤𝙬 𝙅𝙖𝙫𝙖? — 𝙋𝙖𝙧𝙩 31

#Java #SoftwareEngineering

[Bharat Singh @Bharatastic]

𝗖𝗹𝗮𝘀𝘀 𝘃𝘀 𝗢𝗯𝗷𝗲𝗰𝘁 -
𝗪𝗵𝗮𝘁 𝗱𝗼 𝘁𝗵𝗲𝘆 𝗿𝗲𝗮𝗹𝗹𝘆 𝗺𝗲𝗮𝗻?

[Bharat Singh @Bharatastic]

𝗢𝗯𝗷𝗲𝗰𝘁𝘀:
• A 𝗿𝗲𝗮𝗹-𝘄𝗼𝗿𝗹𝗱 𝗲𝗻𝘁𝗶𝘁𝘆, live in memory.
• Every object is an 𝗶𝗻𝘀𝘁𝗮𝗻𝗰𝗲 𝗼𝗳 𝗮 𝗰𝗹𝗮𝘀𝘀.
• Objects can not be created directly.
• Objects have their own state and identity.