Multiple choice technology programming languages

In Java, to copy the contents of a to a new Foo object b

  1. Foo b = a;

  2. Foo b = a.clone();

  3. Foo b;b=a;

  4. -
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Foo b = a.clone() is correct because calling clone() creates a new object with the same contents as the original. Foo b = a (A) only copies the reference, not the object itself. Foo b; b=a (C) is the same as A. Option D is invalid.

AI explanation

In Java, simple assignment (Foo b = a;) just copies the reference, so b and a point to the same object — no new object is created. To actually copy the contents into a new Foo object, you need Object.clone() (with Foo implementing Cloneable and overriding clone() appropriately), giving Foo b = a.clone();. This creates a distinct object with copied field values (shallow copy by default). 'Foo b; b = a;' is equivalent to the first wrong option — still just reference assignment, not a copy — and the dash option is not a valid answer at all.

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