5. Working with Strings, Arrays and ArrayLists

Question 1

True or False: All string methods use zero-based indexes ?

Answer 1

There is only one exception - the second argument of
substring() is not zero-based.

Question 2

When we are talking about Strings and Arrays - length() or length ?

Answer 2

Strings have a method called length()—arrays have an attribute named length.

Question 3

What is the difference when you create an array of objects and an array of primitives.

Answer 3

Elements in an array of objects are not automatically created, although primitive array elements are given default values.

Question 4

Can a byte variable go in an int array ?

Answer 4

An array of primitives can accept any value that can be promoted implicitly to the array’s declared type, so the answer is yes - a byte variable can go in an int array.

Question 5

Which of the following will compile successfully:

int eArr1[] = {10, 23, 10, 2};
int[] eArr2 = new int[10];
int[] eArr3 = new int[] {};
int[] eArr4 = new int[10] {};
int eArr5[] = new int[2] {10, 20};

Answer 5

Defining the size of the array while using {} is not correct. Both of the following lines of code are correct:

int[] eArr4 = new int[10];
int[] eArr4 = new int[]{};