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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.
So let’s start the quiz!!!
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Question 1 of 23
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);
}
}
}
Question 2 of 23
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);
}
}
Question 3 of 23
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);
}
}
Question 4 of 23
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);
}
}
}
Question 5 of 23
Which of those doesn’t have an index based structure?
Question 6 of 23
java.util.Collections is a:
Question 7 of 23
Methods such as reverse, shuffle are offered in:
Question 8 of 23
Which of those allows duplicate elements?
Question 9 of 23
Which allows the storage of a null key and null values?
Question 10 of 23
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);
}
}
Question 11 of 23
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”);
Iterator<String> iterator=vector.iterator();
while(iterator.hasNext())
{
System.out.println(iterator.next());
}
}
}
Question 12 of 23
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);
}
}
Question 13 of 23
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>();
arrayList.add(“a”);
arrayList.add(“b”);
arrayList.add(“c”);
System.out.println();
arrayList.add(1,”d”);
System.out.println(arrayList);
}
}
Question 14 of 23
What will be the output of the following code
import java.util.List;
public class ArrayListTest {
public static void main(String args[])
{
List<String> arrayList=new ArrayList<String>();
arrayList.add(“a”);
arrayList.add(“a”);
arrayList.clear();
arrayList.add(“b”);
arrayList.add(“b”);
System.out.println(arrayList.size());
}
}
Question 15 of 23
What will be the output of the following code
import java.util.Map;
import java.util.TreeMap;
public class TreeMapTest {
public static void main (String args[])
{
Map<Integer,String> m= new TreeMap<Integer,String>();
m.put(11, “audi”);
m.put(null, null);
m.put(11,”bmw”);
m.put(null,”fer”);
System.out.println(m.size());
System.out.println(m);
}
}
Question 16 of 23
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);
}
}
Question 17 of 23
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));
}
public static double sum(List<? extends Number> list)
{
double sum=0;
for(Number num:list)
{
sum+=num.doubleValue();
}
return sum;
}
}
Question 18 of 23
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);
}
}
Question 19 of 23
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); {
Set<Integer> treeSet=new TreeSet<Integer>(collection);
System.out.println(treeSet);
}
}
}
Question 20 of 23
Which interface should be implemented for sorting on basis of many criteria’s?
Question 21 of 23
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);
}
}
}
Question 22 of 23
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));
}
}
Question 23 of 23
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
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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Akila T says:
I’m not getting my score. Help please.
DataFlair Team says:
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
Ajith says:
is that the 14th question’s answer is correct? can you explain to me why?
ancy says:
can you explain how did you get the answer to the 14th question?
Bhuvaneswari says:
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
sanjay.b says:
nice skills to build our knowledge
DataFlair Team says:
Thanks Sanjay for liking the Java Quiz by DataFlair. Do check our side bar for more such interesting quizzes.
Aka Ace says:
4th question : Answer is Runtime exception
DataFlair Team says:
Thanks for highlighting the mistake, we have checked and corrected the same in Java Quiz.
anil says:
Answer for problem 4 is incorrect
DataFlair Team says:
Thanks for highlighting the mistake, we have checked and corrected the same in Java Quiz.
Swarna Sukanta says:
Please let me know the answer of question no 21.
Vishal says:
consider one question as 1 marks
R.kalpana says:
Java
Janice M. Garcia says:
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
nabita waluka says:
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
Zikrillo Islomov says:
Q10,
output will be different it is incorrect
sadak abdulle says:
sadak abdullahi rage I want more quiz of java
Chaitra says:
10th Answer look like
5{null=null, 2=ayushi, 7= renuka, 9…., 11…}
Bongani Mguni says:
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
Phumelele Miya says:
Awesomeness 👌
Phumelele Miya says:
Already passed
sureshreddy mallakuntla says:
is that the 4th question answer is correct? can you explain to me How.
Gozde Apak says:
2th question : [1,3,2]
preksha bhalani says:
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
Rahul Kumar Sah says:
in the 2nd question LinkedHashSet remove the duplicate buy in the answer duplicate output give how
abel says:
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.?