14. Arrays

Question 1

Does an array object have a variable or a fixed size?

Answer 1

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Question 2

Do we need to change the program source code in order to change the size of an array used by a program?

Answer 2

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Question 3

Which of the following variable declarations are legal?

1. int {} smallPrimes = {2, 3, 5, 7, 11, 13, 17, 19};
2. int [] smallPrimes = [2, 3, 5, 7, 11, 13, 17, 19];
3. int [] smallPrimes = {2, 3, 5, 7, 11, 13, 17, 19};
4. int {} smallPrimes = [2, 3, 5, 7, 11, 13, 17, 19];

Answer 3

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Question 4

How many in variables are created by the following code?

int[][] anArray = new int[4][];
for (int index = 0; index < anArray.length; index++)
anArray[index] = new int[index];

Answer 4

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Question 5

How many references are involved in the following?

int[][] my2DArray = new int[5][4]

Answer 5

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Question 6

What set of indices does an array of ten elements have?

Answer 6

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Question 7

Consider the following.
int[][] my2DArray = new int[5][4];

Which element is acces by my2DArray[4][1]?

1. The first element in the last row.
2. The second element in the last row.
3. The first element in the penultimate row.
4. The fourth element in the first row.
5. The third element in the first row.

Answer 7

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Question 8

How do we find the length of an array?

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Question 9

What is the difference between and array variable containing null, and one containing a reference to an empty array?

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Question 10

What does an ‘array of objects’ contain?

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Question 11

What other variable do we need to support a partially filled array?

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Question 12

What is the minimum size increase when extending an array? What is a good size increase?

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Question 13

What is the difference between shallow and deep copies?

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Question 14

How does linear search in a list work?

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Question 15

Give three examples of a sort order on simple data, such as numbers or names.

Answer 15

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Question 16

When using bubble sort for an array of length n, how many pair comparisons are needed worst case? (I.e. how many passes, and how many pairs on each pass?

Answer 16

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Question 17

What is the essential difference between double division by zero and that of integer division?

Answer 17

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Question 18

Which of the following expressions could produce an exception, where size and sum are int variables?

1. size == 0 || sum / size >= 0
2. sum / size < 10 && size != 0

Answer 18

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Question 19

What is the most obvious example of accepting parameters of an array type?

Answer 19

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Question 20

In what sense does a method never return an array?

Answer 20

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Question 21

What is the return type of the round() method?

Answer 21

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Question 22

How do we use Scanner to read every line of a file?

Answer 22

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Question 23

What is the difference between format() and System.out.printf()?

Answer 23

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Question 24

What does the split() method do?

Answer 24

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Question 25

What happens if the item matching “%s” is not a string?

Answer 25

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Question 26

What is the output by the following?

System.out.printf(“From %s to %s is %1.2f miles.%n”, “here”, “eternity”, 1.0/0);

Answer 26

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Question 27

When talking about System.out.printf(), then what is the difference between right and left justification, and how do we obtain each one?

Answer 27

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Question 28

When should we use a for-each loop? In particular, what can it not do?

Answer 28

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Question 29

What are enum types used for?

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Question 30

How do we use an enum type defined in another class?

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Question 31

How do we write the type of an array which has a String base type?

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Question 32

What benefits does class constants and a set if its choices have, compared with using the integer values directly?

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Question 33

What are the dangers of class constant and a set of its choices approach?

Answer 33

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Question 34

In what sense does an array type variable never contain and array?

Answer 34

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