If a class defines no constructor, what happens?

If a class defines no constructor, what happens?

• A. If no constructor is defined, the language provides a default no-argument constructor.
• B. Default constructors can take arguments.
• C. A class cannot have both a default and a parameterized constructor.
• D. Default constructors must be explicitly declared.

Answer: (A)

When you do not define any constructor, the language automatically provides a parameterless constructor. This implicit constructor lets you create objects without passing arguments, and the instance fields are initialized to their default values (like zero, false, or null, depending on the type). If you later add a constructor that takes parameters, that automatic no-argument constructor is no longer generated, so you would need to declare a no-argument constructor explicitly if you still want to be able to instantiate with no arguments. This is why the statement that a default no-argument constructor is provided when none is defined is the correct one. The other options conflict with how implicit constructors work and with the fact that you can have both a no-argument and a parameterized constructor when you explicitly provide them.

When you do not define any constructor, the language automatically provides a parameterless constructor. This implicit constructor lets you create objects without passing arguments, and the instance fields are initialized to their default values (like zero, false, or null, depending on the type). If you later add a constructor that takes parameters, that automatic no-argument constructor is no longer generated, so you would need to declare a no-argument constructor explicitly if you still want to be able to instantiate with no arguments. This is why the statement that a default no-argument constructor is provided when none is defined is the correct one. The other options conflict with how implicit constructors work and with the fact that you can have both a no-argument and a parameterized constructor when you explicitly provide them.