Which construct creates a new object by copying state from an existing object using a constructor?

Which construct creates a new object by copying state from an existing object using a constructor?

• A. Copy constructor
• B. Clone method
• C. Builder pattern
• D. Factory method

Answer: (A)

Copying an object’s state during creation is done with a copy constructor. A copy constructor is a constructor that takes another object of the same class as a parameter and uses that object’s fields to initialize the new one. This creates a brand-new instance that starts with the same data as the original, so the two objects are distinct, though how deeply the data is copied can vary: you might copy references as-is (shallow copy) or create independent copies of nested objects (deep copy) depending on the language and implementation. The clone method is a separate mechanism that duplicates an object via a method rather than a constructor, and it can introduce complexity like returning a generic type or handling deep vs shallow copies. The builder pattern constructs a new object through a step-by-step process using a separate builder, not by copying an existing object's state. The factory method encapsulates object creation behind a method, but it does not duplicate the state of an existing instance. So the construct described—creating a new object by copying state from an existing object using a constructor—is the copy constructor.

Copying an object’s state during creation is done with a copy constructor. A copy constructor is a constructor that takes another object of the same class as a parameter and uses that object’s fields to initialize the new one. This creates a brand-new instance that starts with the same data as the original, so the two objects are distinct, though how deeply the data is copied can vary: you might copy references as-is (shallow copy) or create independent copies of nested objects (deep copy) depending on the language and implementation. The clone method is a separate mechanism that duplicates an object via a method rather than a constructor, and it can introduce complexity like returning a generic type or handling deep vs shallow copies. The builder pattern constructs a new object through a step-by-step process using a separate builder, not by copying an existing object's state. The factory method encapsulates object creation behind a method, but it does not duplicate the state of an existing instance. So the construct described—creating a new object by copying state from an existing object using a constructor—is the copy constructor.