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As you progress in your Java development journey, solidifying your understanding of core concepts and functionalities is paramount. Regular self-assessment is crucial for identifying areas of strength and weakness, allowing you to tailor your learning and ensure well-rounded knowledge.
Java quiz questions offer an excellent platform for such self-assessment, providing a focused and engaging way to test your Java skills.
This blog post presents a set of 25 multiple-choice Java quiz questions encompassing various aspects of the language. These questions delve into fundamental syntax, data structures, object-oriented programming (OOP) principles, and commonly used libraries. By actively engaging with this quiz, you can gain valuable insights into your current level of Java comprehension.
Here, we are providing you with some multiple choice questions of Java with answers. This java quiz will help you to brush up Java concepts.
Do not forget to check other java quizzes as well from the series of 7 Java Quizzes.
What will be the output of the following code import java.util.Arrays; import java.util.Comparator; public class ComparatorTest { public static void main(String args[]) { String[] ar= {“c”,”d”,”b”,”a”,”e”}; InnerClass in=new InnerClass(); Arrays.parallelSort(ar, in); for(String str : ar) System.out.println(str +””); System.out.println(Arrays.binarySearch(ar, “b”)); } static class InnerClass implements Comparator<String> { public int compare(String s1, String s2) { return s2.compareTo(s1); } } }
Correct
Incorrect
Question 2 of 23
2. Question
What will be the output of the following code import java.util.LinkedHashSet; import java.util.Set; public class LinkedHashSetTest { public static void main (String args[]) { Set s=new LinkedHashSet(); s.add(“1”); s.add(1); s.add(3); s.add(2); System.out.println(s); } }
Correct
Incorrect
Question 3 of 23
3. Question
What will be the output of the following code import java.util.ArrayList; import java.util.Collections; import java.util.Comparator; class Employee implements Comparator{ String name; String id; public Employee() {} public Employee(String name, String id) { this.name=name; this.id=id; } @Override public int compare(Employee obj1, Employee obj2) { return obj2.name.compareTo(obj1.name); } @Override public String toString() { return “{“+”name “+name+”, id ” + id+’}’; } } public class ComparatorUsage { public static void main(String args[]) { Employee emp1=new Employee(“sam”,”4″); Employee emp2=new Employee(“amy”,”2″); ArrayList<Employee> list=new ArrayList<Employee>(); list.add(emp1); list.add(emp2); Collections.sort(list,new Employee()); System.out.println(list); }
}
Correct
Incorrect
Question 4 of 23
4. Question
What will be the output of the following code import java.util.ArrayList; import java.util.List; public class ListDemo {
public static void main (String args[]) { List<Integer> list=new ArrayList<Integer>(); list.add(2); list.add(3); m(list); public static void m(List<Number> list) { System.out.println(list); } }
}
Correct
Incorrect
Question 5 of 23
5. Question
Which of those doesn’t have an index based structure?
Correct
Incorrect
Question 6 of 23
6. Question
java.util.Collections is a:
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Incorrect
Question 7 of 23
7. Question
Methods such as reverse, shuffle are offered in:
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Incorrect
Question 8 of 23
8. Question
Which of those allows duplicate elements?
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Incorrect
Question 9 of 23
9. Question
Which allows the storage of a null key and null values?
Correct
Incorrect
Question 10 of 23
10. Question
What will be the output of the following code import java.util.HashMap; import java.util.Map; public class HashMapTest { public static void main(String args[]) { Map<Integer,String> hashMap=new HashMap<Integer,String>(); hashMap.put(11,”animesh”); hashMap.put(2,”ayushi”); hashMap.put(7,”renuka”); hashMap.put(9,”shivashish”); hashMap.put(null,”null”); System.out.println(hashMap.size()); System.out.println(hashMap); }
}
Correct
Incorrect
Question 11 of 23
11. Question
What will be the output of the following code import java.util.Iterator; import java.util.Vector;
public class VectorTest { public static void main(String args[]) { Vector<String> vector= new Vector<String>(); vector.add(“1”); vector.add(“2”);
What will be the output of the following code import java.util.ArrayList; import java.util.List;
public class MyClass { public static void main (String args[]) { //Insert Here List<String> list=new ArrayList<String>(); list.add(“a”); list.add(“b”); l.add(list);
} }
Correct
Incorrect
Question 13 of 23
13. Question
What will be the output of the following code import java.util.ArrayList; import java.util.List;
public class ArrayListTest { public static void main(String args[]) { List<String> arrayList=new ArrayList<String>();
What will be the output of the following code class PrintValue { <t> void display(t obj[]) { for(t i:obj) { System.out.println(i+” “); } } } public class MyClass { public static void main(String…args) { Abc obj1=new Abc();
Integer i[]= {1,2}; obj1.display(i);
Double d[]= {1.1,2.2}; obj1.display(d); } }
Correct
Incorrect
Question 17 of 23
17. Question
What will be the output of the following code import java.util.ArrayList; import java.util.List;
public class MyClass { public static void main (String args[]) { List<Integer> list=new ArrayList<Integer>(); list.add(2); list.add(3); System.out.println(sum(list));
What will be the output of the following code import java.util.Comparator;
public class SortSet { public static void main(String…a) { Set<Integer> treeSet=new TreeSet(new Comparator<Integer>() { public int compareTo(Integer o1,Integer o2) { return o2.compareTo(o1); } }); treeSet.add(3); treeSet.add(1); treeSet.add(2); System.out.println(treeSet);
}
}
Correct
Incorrect
Question 19 of 23
19. Question
What will be the output of the following code import java.util.Collection; import java.util.HashSet; import java.util.Set; import java.util.TreeSet;
public class SortSet { public static void main(String…a) { Collection<Integer> collection = new HashSet<Integer>(); collection.add(3); collection.add(1); collection.add(2); {
Which interface should be implemented for sorting on basis of many criteria’s?
Correct
Incorrect
Question 21 of 23
21. Question
What will be the output of the following code import java.util.Comparator; import java.util.Map; import java.util.TreeMap; public class SortMap {
public static void main(String…a) { Map<Integer,Integer> treeMap = new TreeMap<Integer,Integer>(new Comparator<Integer>() { public int compare(Integer o1,Integer o2) { return o2.compareTo(o1); } }); treeMap.put(4,1); treeMap.put(2,1); treeMap.put(3,1);{
System.out.println(treeMap);
} } }
Correct
Incorrect
Question 22 of 23
22. Question
What will be the output of the following code import java.util.List; import java.util.ArrayList;
public class MyClass {
public static void main(String…a) { List<Integer> l = new ArrayList<Integer>(); l.add(2); m(1); } static void m(List<? super Double> l) { System.out.println(l.get(0)); System.out.println(l.get(1)); } }
Correct
Incorrect
Question 23 of 23
23. Question
In ConcurrentHashMap – once thread locks one segment for updation it doesn’t allow the other thread to perform updations in the same segment till lock isn’t released on the segment
Correct
Incorrect
Summary:
While attempting the quiz, strive to answer each question to the best of your ability. For questions you answer correctly, you can reinforce your understanding of those specific topics.
Conversely, questions that pose a challenge pinpoint areas requiring further exploration. Don’t be discouraged by encountering difficult questions; instead, view them as opportunities to target your learning efforts.
The answer key provided after the quiz allows you to verify your responses and identify any misconceptions. For incorrect answers, revisit the corresponding Java concepts in your learning materials or online tutorials. By dedicating focused study time to these areas, you can effectively address any knowledge gaps and solidify your overall Java foundation.
Remember, the goal of this quiz is not to achieve a perfect score but to gain valuable insights into your Java proficiency. By actively engaging with these questions, identifying areas for improvement, and dedicating time to targeted learning, you can take significant strides towards mastering Java and achieving your development goals.
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Hi Akila, Thanks for taking this Java Quiz. We have checked the Quiz and all its settings, everything is working fine. Please ensure you filled all the answers (mandatory), and after submitting your email id, you will get your score on the screen with the answers you have provided. Regards, DataFlair
in that program they have cleared thelist in the 4th line list clear() so the actuall initial values are totally washed out then the further values are stored.so that the size is 2 i guess
Most application software programmer will not need to use the Comparator.compare() to see if they are equal, especially with Strings. You use equal() with Strings. compareTo() =0 does not imply equality in all cases!!! The only time to use this would be for creating a Dictionary of words sorted in ascending order. A
Hi, i am happy with our quiz questions and everything works well. its very helpful but i suggest that you and an explanations to the correct answers for many learners like me to understand fully. i thank you
for question 4 its compile exception because the java generics are not covariant meaning evn if integers is a subtype of numbers its does not mean list type integers is a subtype of list type numbers
16. Question What will be the output of the following code class PrintValue { void display(t obj[]) { for(t i:obj) { System.out.println(i+” “); } } } public class MyClass { public static void main(String…args) { Abc obj1=new Abc();
Integer i[]= {1,2}; obj1.display(i);
Double d[]= {1.1,2.2}; obj1.display(d); } }
It should give the error because of the class name PrintValue and we are calling Abc
I don’t really get it. Description says “various aspects of Java” but all I see in these seven quizzes are Tree, Hash, Map, Set, Vector,… Where are all the more “core” stuff, methods, strings, arrays, flow control, core algorithms like swapping elements in array or string manipulations, etc.?
I’m not getting my score. Help please.
Hi Akila,
Thanks for taking this Java Quiz. We have checked the Quiz and all its settings, everything is working fine. Please ensure you filled all the answers (mandatory), and after submitting your email id, you will get your score on the screen with the answers you have provided.
Regards,
DataFlair
is that the 14th question’s answer is correct? can you explain to me why?
can you explain how did you get the answer to the 14th question?
in that program they have cleared thelist in the 4th line list clear()
so the actuall initial values are totally washed out then the further values are stored.so that the size is 2 i guess
nice skills to build our knowledge
Thanks Sanjay for liking the Java Quiz by DataFlair. Do check our side bar for more such interesting quizzes.
4th question : Answer is Runtime exception
Thanks for highlighting the mistake, we have checked and corrected the same in Java Quiz.
Answer for problem 4 is incorrect
Thanks for highlighting the mistake, we have checked and corrected the same in Java Quiz.
Please let me know the answer of question no 21.
consider one question as 1 marks
Java
Most application software programmer will not need to use the Comparator.compare() to see if they are equal, especially with Strings. You use equal() with Strings. compareTo() =0 does not imply equality in all cases!!! The only time to use this would be for creating a Dictionary of words sorted in ascending order. A
Hi, i am happy with our quiz questions and everything works well. its very helpful but i suggest that you and an explanations to the correct answers for many learners like me to understand fully.
i thank you
Q10,
output will be different it is incorrect
sadak abdullahi rage I want more quiz of java
10th Answer look like
5{null=null, 2=ayushi, 7= renuka, 9…., 11…}
for question 4 its compile exception because the java generics are not covariant meaning evn if integers is a subtype of numbers its does not mean list type integers is a subtype of list type
numbers
Awesomeness 👌
Already passed
is that the 4th question answer is correct? can you explain to me How.
2th question : [1,3,2]
16. Question
What will be the output of the following code
class PrintValue
{
void display(t obj[])
{
for(t i:obj)
{
System.out.println(i+” “);
}
}
}
public class MyClass {
public static void main(String…args)
{
Abc obj1=new Abc();
Integer i[]= {1,2};
obj1.display(i);
Double d[]= {1.1,2.2};
obj1.display(d);
}
}
It should give the error because of the class name PrintValue and we are calling Abc
in the 2nd question LinkedHashSet remove the duplicate buy in the answer duplicate output give how
I don’t really get it. Description says “various aspects of Java” but all I see in these seven quizzes are Tree, Hash, Map, Set, Vector,… Where are all the more “core” stuff, methods, strings, arrays, flow control, core algorithms like swapping elements in array or string manipulations, etc.?