Arrays and ArrayLists Flashcards
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What happens if you try to store a double value in an int array in Java?
Answer: Compile-time error
Java is strongly typed; storing a double in an int array causes a compile-time type mismatch error.
How do you get the number of rows in a 2D array called `matrix`?
Answer: matrix.length
For a 2D array, `matrix.length` gives the number of rows (outer array length).
Which ArrayList method removes the first occurrence of a specified object?
Answer: remove(Object o)
ArrayList.remove(Object o) removes the first occurrence of the specified element from the list.
What is traversing a 2D array row by row called?
Answer: Row-major order traversal
Iterating through a 2D array row by row (outer loop over rows) is called row-major order traversal.
What is the default value of elements in a newly created `int[]` array?
Answer: 0
Java initializes all elements of a numeric array to 0 by default when created with `new`.
Which of the following correctly converts an ArrayList to an array?
Answer: list.toArray(new Integer[0])
The toArray(T[] a) method of ArrayList returns an array containing all elements; passing `new Integer[0]` specifies the type.