Core Java

Collections Objective Questions And Answers
More interview questions and answers

Consider the following program: import myLibrary.*; public class ShowSomeClass { // code for the class... } What is the name of the java file containing this program? A. myLibrary.java B. ShowSomeClass.java C. ShowSomeClass D. ShowSomeClass.class E. Any file name with the java suffix will do

Which of the following is TRUE? A. In java, an instance field declared public generates a compilation error. B. int is the name of a class available in the package java.lang C. Instance variable names may only contain letters and digits. D. A class has always a constructor (possibly automatically supplied by the java compiler).

Consider the following code snippet String river = new String(“Columbia”); System.out.println(river.length()); What is printed? A. 6 B. 7 C. 8 D. Columbia

A constructor A. must have the same name as the class it is declared within. B. is used to create objects. C. may be declared private D. A and B E. A, B and C

Which of the following may be part of a class definition? A. instance variables B. instance methods C. constructors D. all of the above

Which class does not override the equals() and hashCode() methods, inheriting them directly from class Object?

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? A. TreeMap B. HashMap C. LinkedHashMap D. The answer depends on the implementation of the existing instance.

Which class does not override the equals() and hashCode() methods, inheriting them directly from class Object? A. java.lang.String B. java.lang.Double C. java.lang.StringBuffer D. java.lang.Character

Which collection class allows you to grow or shrink its size and provides indexed access to its elements, but whose methods are not synchronized? A.java.util.HashSet B.java.util.LinkedHashSet C.java.util.List D.java.util.ArrayList

You need to store elements in a collection that guarantees that no duplicates are stored. Which one of the following interfaces provide that capability? A.Java.util.Map B.Java.util.List C.Java.util.Collection D.None of the above

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? A. java.util.Map B. java.util.Set C. java.util.List D. java.util.Collection

6. Which interface does java.util.HashTable implement? A.Java.util.Map B.Java.util.List C.Java.util.HashTable D.Java.util.Collection

Which interface provides the capability to store objects using a key-value pair? A.Java.util.Map B.Java.util.Set C.Java.util.List D.Java.util.Collection

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? A.java.util.ArrayList B.java.util.LinkedHashMap C.java.util.HashMap D.java.util.TreeMap

Which collection class allows you to access its elements by associating a key with an element's value, and provides synchronization? A.java.util.SortedMap B.java.util.TreeMap C.java.util.TreeSet D.java.util.Hashtable

Which is valid declaration of a float? A.float f = 1F; B.float f = 1.0; C.float f = "1"; D.float f = 1.0d;

11. /* Missing Statement ? */public class foo { public static void main(String[]args)throws Exception { java.io.PrintWriter out = new java.io.PrintWriter(); new java.io.OutputStreamWriter(System.out,true); out.println(\"Hello\"); } } A.No statement required. B.import java.io.*; C.include java.io.*; D.import java.io.PrintWriter;

What is the numerical range of char? A.0 to 32767 B.0 to 65535 C.-256 to 255 D.-32768 to 32767

Which of the following are Java reserved words? run import default implement A.1 and 2 B.2 and 3 C.3 and 4 D.2 and 4