Java - Objects and Collections
Java - Objects and Collections
1. Suppose that you would like to create an instance of a new Map that has an iteration order that is the same as the iteration order of an existing instance of a Map. Which concrete implementation of the Map interface should be used for the new instance?
- TreeMap
- HashMap
- LinkedHashMap
- The answer depends on the implementation of the existing instance.
2. Which class does not override the equals() and hashCode() methods, inheriting them directly from class Object?
- java.lang.String
- java.lang.Double
- java.lang.StringBuffer
- java.lang.Character
3. Which collection class allows you to grow or shrink its size and provides indexed access to its elements, but whose methods are not synchronized?
- java.util.HashSet
- java.util.LinkedHashSet
- java.util.List
- java.util.ArrayList
4. You need to store elements in a collection that guarantees that no duplicates are stored. Which one of the following interfaces provide that capability?
- Java.util.Map
- Java.util.List
- Java.util.Collection
- None of the above
5. You need to store elements in a collection that guarantees that no duplicates are stored and all elements can be accessed in natural order. Which interface provides that capability?
- java.util.Map
- java.util.Set
- java.util.List
- java.util.Collection
6. Which interface does java.util.HashTable implement?
- Java.util.Map
- Java.util.List
- Java.util.HashTable
- Java.util.Collection
7. Which interface provides the capability to store objects using a key-value pair?
- Java.util.Map
- Java.util.Set
- Java.util.List
- Java.util.Collection
8. Which collection class allows you to associate its elements with key values, and allows you to retrieve objects in FIFO (first-in, first-out) sequence?
- java.util.ArrayList
- java.util.LinkedHashMap
- java.util.HashMap
- java.util.TreeMap
9. Which collection class allows you to access its elements by associating a key with an element's value, and provides synchronization?
- java.util.SortedMap
- java.util.TreeMap
- java.util.TreeSet
- java.util.Hashtable
10. Which is valid declaration of a float?
- float f = 1F;
- float f = 1.0;
- float f = "1";
- float f = 1.0d;