CS122

Question 1

What does nextInt(max) do?

Answer 1

Returns a random integer from 0 to max-1.

Question 2

What does nextDouble() do?

Answer 2

Returns a random real number between 0.0 to 1.0.

Question 3

What does contains(str) do?

Answer 3

Returns true if this string contains str inside.

Question 4

What does endsWith(str) do?

Answer 4

Returns true if this string ends with str.

Question 5

What does startsWith(str) do?

Answer 5

Returns true if this string starts with str.

Question 6

What does equals(str) do?

Answer 6

Returns true if this string is the same as str.

Question 7

What does equalsIgnoreCase(str) do?

Answer 7

Returns true if this string is the same as str, ignoring capitalization.

Question 8

What does indexOf(str) do?

Answer 8

Returns the index in this string where given str begins (-1 if not found).

Question 9

What does length() do?

Answer 9

Returns the number of characters in this string.

Question 10

What does substring(i,j) do?

Answer 10

Returns characters in this string from index i (inclusive) to index j (exclusive).

Question 11

What does toLowerCase() do?

Answer 11

Returns a new string with all lowercase characters.

Question 12

What does toUpperCase() do?

Answer 12

Returns a new string with all uppercase characters.

Question 13

What does charAt(i) do?

Answer 13

Returns the character at index i.

Question 14

What does add(index, value) do in List<E>?</E>

Answer 14

Inserts given value at given index, shifting subsequent values right.

Question 15

What does add(value) do in List<E>?</E>

Answer 15

Inserts given value at the end of the list.

Question 16

What does contains(value) do in List<E>?</E>

Answer 16

Returns true if the given value is found, false otherwise.

Question 17

What does indexOf(value) do in List<E>?</E>

Answer 17

Returns the first index where given value is found in the list (-1 if not found).

Question 18

What does get(index) do in List<E>?</E>

Answer 18

Returns the value at given index.

Question 19

What does remove(value) do in List<E>?</E>

Answer 19

Removes/returns value at given index, shifting subsequent values left.

Question 20

What does set(index, value) do in List<E>?</E>

Answer 20

Replaces value at given index with given value.

Question 21

What does peek() do in Stack<E>?</E>

Answer 21

Returns the top value from the stack without removing it.

Question 22

What does pop() do in Stack<E>?</E>

Answer 22

Removes the top value from the stack and returns it.

Question 23

What does push(value) do in Stack<E>?</E>

Answer 23

Places the given value on top of the stack.

Question 24

What does size() do in Stack<E>?</E>

Answer 24

Returns the number of elements in the stack.

Question 25

What does isEmpty() do in Stack?

Answer 25

Returns true if stack has no elements.

Question 26

What does add(value) do in Queue?

Answer 26

Places the given value at the back of the queue.

Question 27

What does peek() do in Queue?

Answer 27

Returns the front value from the queue without removing it.

Question 28

What does remove() do in Queue?

Answer 28

Removes the value from the front of the queue and returns it.

Question 29

What does size() do in Queue?

Answer 29

Returns the number of elements in the queue.

Question 30

What does isEmpty() do in Queue?

Answer 30

Returns true if queue has no elements.

Question 31

What does containsKey(key) do in Map?

Answer 31

Returns true if the map contains a mapping for the given key.

Question 32

What does get(key) do in Map?

Answer 32

Returns the value mapped to the given key (null if none).

Question 33

What does keySet() do in Map?

Answer 33

Returns a Set of all keys in the map.

Question 34

What does put(key, value) do in Map?

Answer 34

Adds a mapping from the given key to the given value.

Question 35

What does putAll(map) do in Map?

Answer 35

Adds all key/value pairs from the given map to this map.

Question 36

What does remove(key) do in Map?

Answer 36

Removes any existing mapping for the given key.

Question 37

What does toString() do in Map?

Answer 37

Returns a string such as “{a=90, b=30, c=29}”.

Question 38

What does values() do in Map?

Answer 38

Returns a Collection of all values in the map.

Question 39

How do you declare a List of Integers?

Answer 39

List list = new ArrayList();

Question 40

How do you declare a Stack of Integers?

Answer 40

Stack s = new Stack();

Question 41

How do you declare a Queue of Integers?

Answer 41

Queue q = new LinkedList();

Question 42

How do you declare a Set of Strings?

Answer 42

Set words = new HashSet();

Question 43

How do you declare a Map of Strings to Integers?

Answer 43

Map counts = new TreeMap();

Question 44

What is the purpose of the method isConsecutive?

Answer 44

The method isConsecutive checks if a stack of integers contains a sequence of consecutive integers starting from the bottom of the stack.

Question 45

What should isConsecutive return for the stack [3, 4, 5, 6, 7, 8, 9, 10]?

Answer 45

It should return true.

Question 46

What should isConsecutive return for the stack [3, 4, 5, 6, 7, 8, 9, 10, 12]?

Answer 46

It should return false.

Question 47

What should isConsecutive return for the stack [3, 2, 1]?

Answer 47

It should return false.

Question 48

What is the behavior of the method removeShorterStrings?

Answer 48

The method removes the shorter string from each successive pair in an ArrayList of Strings.

Question 49

What happens if there is a tie in removeShorterStrings?

Answer 49

The first string in the pair is removed.

Question 50

What does the method minToFront do?

Answer 50

The method moves the minimum value in an ArrayList of integers to the front while preserving the order of the elements.

Question 51

What is the output of minToFront for the list {3, 8, 92, 4, 2, 17, 9}?

Answer 51

The output should be {2, 3, 8, 92, 4, 17, 9}.

Question 52

What is the purpose of the compareTo method in the Point class?

Answer 52

The compareTo method allows Points to be compared based on their distance from the origin.

Question 53

What does the method removeInRange do?

Answer 53

The method removes all occurrences of a specified element in an ArrayList between a starting and ending index.

Question 54

What is the output of removeInRange for the list [0, 0, 2, 0, 4, 0, 6, 0, 8, 0, 10, 0, 12, 0, 14, 0, 16] with parameters (0, 5, 13)?

Answer 54

The output should be [0, 0, 2, 0, 4, 6, 8, 10, 12, 0, 14, 0, 16].

Question 55

What does the method stutter do?

Answer 55

The method replaces every string in an ArrayList with k copies of that string.

Question 56

What happens if k is 0 or negative in the stutter method?

Answer 56

The list should be empty after the call.

Question 57

What is the purpose of the method removeDuplicates?

Answer 57

The method eliminates duplicates from a sorted ArrayList of Strings.

Question 58

What is the output of removeDuplicates for the list {"be", "be", "is", "not", "or", "question", "that", "the", "to", "to"}?

Answer 58

The output should be {"be", "is", "not", "or", "question", "that", "the", "to"}.

Question 59

What does the method collectionMystery1 do?

Answer 59

The method processes a HashMap and prints a new HashMap based on the comparison of keys and values.

Question 60

What is the output of collectionMystery1 for the map {skate=board, drive=car, program=computer, play=computer}?

Answer 60

The output will be {drive=car, skate=board, program=computer, play=computer}.

Question 61

What does the method search return?

Answer 61

The method returns a set with the most frequent strings from a given string list.

Question 62

What is the output of search for the list ["a", "b", "cd", "cd", "ef", "ef"]?

Answer 62

The output will be a set containing ["cd", "ef"].

Question 63

What does the method that accepts a List of Strings and a Set of Characters do?

Answer 63

It determines the number of times each character is found in the words as a map.

Question 64

What is the output for the set ('b','o') and the List ("book", "love", "born")?

Answer 64

It would return a map {'b' = 2, 'o' = 4}.