If a class has only a parameterized constructor and you attempt to instantiate with no arguments, what happens?

If a class has only a parameterized constructor and you attempt to instantiate with no arguments, what happens?

• A. A compilation error occurs because there is no matching constructor.
• B. An implicit default constructor is inserted.
• C. The runtime calls a parameterized constructor with default values.
• D. The program automatically creates a new constructor at runtime.

Answer: (A)

When a class provides only a parameterized constructor, no default no-argument constructor is created automatically. That means trying to instantiate the class with no arguments has no matching constructor, so the compiler flags an error. The runtime won’t fill in default values or add a constructor at runtime. If you want to create objects without arguments, you need to explicitly define a no-argument constructor (or use a form of constructor overloading or default parameters where the language supports it). This is why a compilation error occurs in this scenario.

When a class provides only a parameterized constructor, no default no-argument constructor is created automatically. That means trying to instantiate the class with no arguments has no matching constructor, so the compiler flags an error. The runtime won’t fill in default values or add a constructor at runtime. If you want to create objects without arguments, you need to explicitly define a no-argument constructor (or use a form of constructor overloading or default parameters where the language supports it). This is why a compilation error occurs in this scenario.