Objects and Collections Questions and Answers
Java Objects and Collections programming questions and answers are essential for mastering object-oriented design and data structure handling. These questions often appear in coding interviews by Infosys, TCS, and Accenture. The topic covers object creation, reference handling, garbage collection, and the use of Java Collection Framework classes like List, Set, and Map. Understanding how to manage and iterate over collections efficiently helps in building optimized programs. Practicing programming questions and answers in this area enhances both logic and coding speed—crucial skills for clearing technical interview rounds and online assessments.
Objects and Collections
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13 questions
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;