Java Maps Review

Which of the following statement about Set is true?

• A HashSet cannot have a null value.

• Set allows duplicate values.

• Set allows null values but only single occurrence.

• Set extends the Java.util.collection interface.

-Entries are organized as key/value pairs.

-Duplicate entries replace old entries.

-Entries are sorted using a Comparator or the Comparable interface.

Which interface of the java.util package offers the specified behavior?

• List

• Map

• Set

• SortedSet

• SortedMap

• {1=C, 2=JavaEE, 4=Python, 3=PHP}

• {1=C, 2=JavaSE, 3=Python, 4=PHP}

• {1=C, 2=JavaEE, 3=Python, 4=PHP}

• {1=C, 2=JavaSE,2=JavaEE, 3=Python, 4=PHP}

• NullPointerException

• {null=null, a=null, b=JavaSE, c=PHP, d=Python}

• {a=null, b=JavaSE, c=PHP, d=Python}

• {b=JavaSE, c=PHP, d=Python}

• Compilation Fails

• 4

• 5

• 6

• 12

Which statement(s) are false about maps in java?

• A Map cannot contain duplicate keys and each key can map to at most one value.

• A Map is an object that maps keys to values, or is a collection of attribute-value pairs.

• A Map cannot contain duplicate keys and each key can map to at more than one value.

• A Map is an object that maps functions to values, or is a collection of attribute-value pairs.

Which of the following TreeMap instantiations would create a TreeMap that could store String-

Integer pairs?

• TreeMap<String,Integer> map;

  map = new TreeMap <String,Integer>();

• TreeMap<Integer,String> map;

  map = new TreeMap <Integer,String>();

• TreeMap<Double,String> map;

  map = new TreeMap <Double,String>();

• TreeMap<Boolean,String> map;

  map = new TreeMap <Boolean,String>();

Which of the following Map methods will add a <key,value> pair to a Map?

• add()

• get()

• set()

• put()

• append()

Which of the following is an interface?

• ArrayList

• HashSet

• TreeMap

• Collection

• LinkedList

Which of the following is a child of SortedMap?

• ArrayList

• HashMap

• TreeMap

• Map

• LinkedList