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Welcome to the java util MCQs Page

Dive deep into the fascinating world of java util with our comprehensive set of Multiple-Choice Questions (MCQs). This page is dedicated to exploring the fundamental concepts and intricacies of java util, a crucial aspect of Java Programming. In this section, you will encounter a diverse range of MCQs that cover various aspects of java util, from the basic principles to advanced topics. Each question is thoughtfully crafted to challenge your knowledge and deepen your understanding of this critical subcategory within Java Programming.

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Check out the MCQs below to embark on an enriching journey through java util. Test your knowledge, expand your horizons, and solidify your grasp on this vital area of Java Programming.

Note: Each MCQ comes with multiple answer choices. Select the most appropriate option and test your understanding of java util. You can click on an option to test your knowledge before viewing the solution for a MCQ. Happy learning!

java util MCQs | Page 6 of 18

Q51.
Which of these methods can be used to obtain set of all keys in a map?
Discuss
Answer: (d).keySet()
Q52.
Which of these method is used add an element and corresponding key to a map?
Discuss
Answer: (a).put()
Q53.
What is the output of this program?
    import java.util.*;
    class Maps 
    {
        public static void main(String args[]) 
        {
            HashMap obj = new HashMap();
            obj.put("A", new Integer(1));
            obj.put("B", new Integer(2));
            obj.put("C", new Integer(3));
            System.out.println(obj);
        }
    }
Discuss
Answer: (d).{A=1, B=2, C=3}
Q54.
What is the output of this program?
    import java.util.*;
    class Maps 
    {
        public static void main(String args[]) 
        {
            HashMap obj = new HashMap();
            obj.put("A", new Integer(1));
            obj.put("B", new Integer(2));
            obj.put("C", new Integer(3));
            System.out.println(obj.keySet());
        }
    }
Discuss
Answer: (a).[A, B, C].
Q55.
Which of these class object can be used to form a dynamic array?
Discuss
Answer: (d).ArrayList & Vector
Q56.
Which of these are legacy classes?
Discuss
Answer: (d).All of the mentioned
Q57.
Which of these is the interface of legacy?
Discuss
Answer: (b).Enumeration
Q58.
What is the name of a data member of class Vector which is used to store a number of elements in the vector?
Discuss
Answer: (c).elementCount
Q59.
Which of these methods is used to add elements in vector at specific location?
Discuss
Answer: (d).addElement()
Q60.
What is the output of this program?
    import java.util.*;
    class vector 
    {
        public static void main(String args[]) 
        {
            Vector obj = new Vector(4,2);
            obj.addElement(new Integer(3));
            obj.addElement(new Integer(2));
            obj.addElement(new Integer(5));
            System.out.println(obj.elementAt(1));
        }
    }

a.

0

b.

3

c.

2

d.

5

Discuss
Answer: (c).2
Page 6 of 18

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