- Dictionaries Complete Test Bank Chapter 20 5th Edition

Chapter 20 - Dictionaries

True/False (17)

1. In the ADT dictionary, search keys and values are paired.
2. The ADT dictionary organizes and identifies its entries by position.
3. Every entry in a dictionary has a search key.
4. Each entry in a dictionary may only have one key.
5. The ADT dictionary requires sorted entries.
6. Whether a dictionary has sorted or unsorted search keys is an implementation detail.
7. You can traverse the dictionary by search keys but not by values.
8. Restricting the ADT dictionary to distinct search keys simplifies the implementation of the remove method.
9. The ADT dictionary does not permit key-null pairs.
10. A key that has no value associated with it does not appear in the dictionary.
11. You cannot traverse a dictionary by both the keys and values in parallel.
12. You can traverse all the keys in a dictionary without traversing the values.
13. You cannot traverse all the values in a dictionary without traversing the keys.
14. A sorted dictionary must use search keys that belong to a class that implements the interface Comparable.
15. The default delimiter for the class Scanner is a white-space character.
16. Duplicate search keys are not permitted in a dictionary that conforms to the Java Class Library Map interface.
17. When using a Scanner object to process text, you can specify any character as a delimiter.

Short Answer (8)

1. Write a statement to create an instance of a class Dictionary that implements DictionaryInterface. Your dictionary contains Word objects that are lists of synonyms for words. The key value is a String representing the word to look up. Call your dictionary thesaurus.
2. Write a statement to create a key iterator for a dictionary called thesaurus that is an instance of the class Dictionary and implements DictionaryInterface. The search keys are strings and the values stored are Word objects.
3. Write a statement to create a value iterator for a dictionary called thesaurus that is an instance of the class Dictionary and implements DictionaryInterface. The search keys are strings and the values stored are Word objects.
4. Malware files are often identified by hash values to uniquely identify the files. Create an instance of an empty dictionary called malware that is a class Dictionary that implements DictionaryInterface. Your dictionary will contain strings for the name of the malware. It will use MDHash objects that contain the hash value as search keys for the malware names.
5. Malware files are often identified by hash values to uniquely identify the files. Given a dictionary called malware that is an instance of the class Dictionary and implements DictionaryInterface with key-value pairs of type String for the filename and MDHash objects for the search key, write a Java statement that adds a malware name that is the string “TrojanDropper” that has an MDHash search-key “55ad340609f4b30”.
6. Malware files are often identified by hash values to uniquely identify the files. Given a dictionary called malware that is an instance of the class Dictionary and implements DictionaryInterface with key-value pairs of type String for the filename and MDHash objects for the search key, write a Java statement that prints the malware associated with the MDHash value “ce54b67080280d1e”. You may assume that the search key is in the dictionary.

System.out.println(“Malware name is “ + malware.getValue(hash));

1. Malware files are often identified by hash values to uniquely identify the files. Given a dictionary called malware that is an instance of the class Dictionary and implements DictionaryInterface with key-value pairs of type String for the filename and MDHash objects for the search key, write a Java statement that prints the malware associated with the MDHash value “ce54b67080280d1e”. You may not assume that the search key is in the dictionary.

if (malware.contains(hash))
System.out.println(“Malware name is “ + malware.getValue(hash));
else
System.out.println(“Malware is not present in the dictionary.”);

1. Malware files are often identified by hash values to uniquely identify the files. Given a dictionary called malware that is an instance of the class Dictionary and implements DictionaryInterface with key-value pairs of type String for the filename and MDHash objects for the search key, write a Java statement that removes and prints an entry from the dictionary given an MDHash object called trojan.

Multiple Choice (22) WARNING: CORRECT ANSWERS ARE IN THE SAME POSITION AND TAGGED WITH . YOU SHOULD RANDOMIZE THE LOCATION OF THE CORRECT ANSWERS IN YOUR EXAM.

1. The ADT dictionary is also known as a(n)
   1. map
   2. table
   3. associative array
   4. all of the above
2. The ADT dictionary has a keyword that is commonly called a(n)
   1. search key
   2. master key
   3. value
   4. all of the above
3. The ADT dictionary contains entries that have a(n)
   1. search key
   2. value
   3. both a & b
   4. none of the above
4. In an ADT dictionary, you use a(n) _____ to locate values.
   1. search key
   2. search value
   3. both a & b
   4. none of the above
5. The ADT dictionary is organized
   1. by key-value pairs
   2. by position
   3. in ascending order
   4. randomly
6. A typical operation of an ADT dictionary is
   1. add a new entry given a search key and value
   2. remove an entry given a search key
   3. retrieve a value associated with a search key
   4. all of the above
7. A typical operation of an ADT dictionary is
   1. determining if the dictionary contains a specific search key
   2. traversing the dictionary by search keys
   3. traversing the dictionary by values
   4. all of the above
8. A typical operation of an ADT dictionary is
   1. traversing the dictionary by values
   2. removing an entry given a value
   3. both a & b
   4. none of the above
9. A useful operation that might be added to the ADT dictionary is
   1. detecting if the dictionary is empty
   2. retrieving the number of dictionary entries
   3. removing all entries from the dictionary
   4. all of the above
10. What ADT dictionary method creates an iterator that traverses all search keys in the dictionary?
    1. getKeyIterator
    2. keyIterator
    3. getKeys
    4. getIterator
11. What ADT dictionary method creates an iterator that traverses all the values in the dictionary?
    1. getValueIterator
    2. getValue
    3. valueIterator
    4. getIterator
12. In the ADT dictionary, a key-null pair
    1. is not stored
    2. is inserted at the beginning of the dictionary
    3. is inserted at the end of the dictionary as a reserve entry
    4. is stored by key-value
13. In the ADT dictionary, you can traverse
    1. all of the search keys without traversing the values
    2. all of the values without traversing the search keys
    3. all of the search keys and all of the values in parallel
    4. all of the above
14. If you create a keyIterator and a valueIterator for the same dictionary, the keyIterator is _____ the valueIterator.
    1. the same length as
    2. larger than
    3. shorter than
    4. none of the above
15. A sorted dictionary must use search keys that belong to a class that implements the interface
    1. Comparable
    2. Sortable
    3. Equals
    4. Searchable
16. The class Scanner can break a string into substrings called
    1. tokens
    2. characters
    3. delimiters
    4. scanbits
17. The class Scanner can break a string into substrings that are separated by
    1. delimiters
    2. separators
    3. tokens
    4. parsers
18. Which method in the class Scanner extracts the tokens from any string?
    1. next
    2. tokenize
    3. split
    4. extract
19. In an ADT dictionary that implements DictionaryInterface, what is returned by the getValue method if the associated search key is not found?
    1. it returns null
    2. it returns 0
    3. it returns false
    4. it throws a KeyNotFoundException
20. A(n) _____ provides the line numbers in a document for each occurrence of a given word.
    1. concordance
    2. index
    3. word counter
    4. line counter
21. In a concordance, the search keys are
    1. words
    2. line numbers
    3. word counts
    4. character counts
22. In a concordance, the values associated with the search keys are
    1. a list of line numbers where a word appears
    2. the number of occurrence of a word in the document
    3. the definition of the word
    4. all of the above