Simple explanation for Builder Pattern

Situation: You’re Creating a User Object

Simple class. A User has:

• name
• email

So you write a constructor. Done.

Then Product Team Comes In

“Actually, we also want to track:”

• phone number
• address
• birthdate
• isSubscribed
• profilePictureUrl
• …and 10 more fields (some optional, some required, some only needed in certain flows).

Now you’re staring at your constructor like:

User user = new User(“John”, “[email protected]”, null, null, true, null, …);

It’s ugly. It’s unreadable. You forget which parameter is which.

And you’re scared to touch it.

What’s the Problem?

• Your constructors are overloaded and confusing.
• Too many optional fields = hard to manage.
• Setting values using setters feels unsafe - object might be in an invalid state.
• Code becomes hard to read and maintain.

How Builder Pattern Saves You

Builder says:

“Don’t pass everything in one shot. Let’s build the object step-by-step - only what you need.”

So instead, you do:

User user = new UserBuilder()
            .withName("John")
            .withEmail("[email protected]")
            .withSubscribed(true)
            .build();

• Clear
• Readable
• No confusion about parameter order
• Object is created only after all the required stuff is set

You can even make the builder validate required fields before allowing .build().

When Should You Use It?

• When object has lots of optional fields
• When constructor overloads are getting out of control
• When you want to enforce immutable, clean object creation
• When chaining setup makes code easier to read

Real World Dev Examples

• StringBuilder in Java
• AlertDialog.Builder in Android
• Request.Builder in OkHttp
• Any API client config objects

Builders are everywhere when the object is complex.