Top 25 Java Quiz Questions – A Small Test to Build Your Knowledge
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Till now, you gained the complete knowledge of Java programming language. So, be ready to test your knowledge with this “Java quiz questions”.
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.
- Java Quiz – 1
- Java Quiz – 2
- Java Quiz – 3
- Java Quiz – 4
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- Question 1 of 23
1. Question
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);
}
}
}CorrectIncorrect - 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);
}
}CorrectIncorrect - 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);
}}
CorrectIncorrect - 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);
}
}}
CorrectIncorrect - Question 5 of 23
5. Question
Which of those doesn’t have an index based structure?
CorrectIncorrect - Question 6 of 23
6. Question
java.util.Collections is a:
CorrectIncorrect - Question 7 of 23
7. Question
Methods such as reverse, shuffle are offered in:
CorrectIncorrect - Question 8 of 23
8. Question
Which of those allows duplicate elements?
CorrectIncorrect - Question 9 of 23
9. Question
Which allows the storage of a null key and null values?
CorrectIncorrect - 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);
}}
CorrectIncorrect - 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”);Iterator<String> iterator=vector.iterator();
while(iterator.hasNext())
{System.out.println(iterator.next());
}
}
}CorrectIncorrect - Question 12 of 23
12. 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[])
{
//Insert Here
List<String> list=new ArrayList<String>();
list.add(“a”);
list.add(“b”);
l.add(list);}
}CorrectIncorrect - 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>();arrayList.add(“a”);
arrayList.add(“b”);
arrayList.add(“c”);System.out.println();
arrayList.add(1,”d”);
System.out.println(arrayList);
}}
CorrectIncorrect - Question 14 of 23
14. Question
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());
}}
CorrectIncorrect - Question 15 of 23
15. Question
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);
}
}CorrectIncorrect - Question 16 of 23
16. Question
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);
}
}CorrectIncorrect - 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));}
public static double sum(List<? extends Number> list)
{
double sum=0;
for(Number num:list)
{
sum+=num.doubleValue();
}
return sum;
}
}CorrectIncorrect - Question 18 of 23
18. Question
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);}
}
CorrectIncorrect - 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); {Set<Integer> treeSet=new TreeSet<Integer>(collection);
System.out.println(treeSet);}
}
}CorrectIncorrect - Question 20 of 23
20. Question
Which interface should be implemented for sorting on basis of many criteria’s?
CorrectIncorrect - 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);
}
}
}CorrectIncorrect - 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));
}
}CorrectIncorrect - 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
CorrectIncorrect
Here we come to the end of the Java Quiz. Hope you enjoyed the quiz!!!
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I’m not getting my score. Help please.
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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