Java Certification Practice Test 2024: Master Your Skills

Q1. What is the result of compiling and running the following program?

public class Learner {
public static void main(String[] args) {
var dataArr = new String[4];
dataArr[1] = "Bill";
dataArr[2] = "Steve";
dataArr[3] = "Larry";
try{
for(String data : dataArr){
System.out.print(data+" ");
}
}catch(Exception e){
System.out.println(e.getClass());
}
}
}

You had to select 1 option(s)

Q2. Given:

Path p1 = Paths.get("c:\\temp\\test1.txt");
Path p2 = Paths.get("c:\\temp\\test2.txt");


Which of the following code fragments moves the file test1.txt to test2.txt, even if test2.txt exists?
Answered Incorrectly

You had to select 2 option(s)

Q3. What will be the result of compilation and execution of the following code ?

IntStream is1 = IntStream.range(0, 5); //1
OptionalDouble x = is1.average(); //2
System.out.println(x); //3

You had to select 1 option(s)

Q4. What will the following code print when run?

class A {
}

class AA extends A {
}


public class TestClass {
public static void main(String[] args) throws Exception {
A a = new A();
AA aa = new AA();
a = aa;
System.out.println("a = "+a.getClass());
System.out.println("aa = "+aa.getClass());
}
}

You had to select 1 option(s)

Q5. Given:

public static void createFile(String name) throws Exception{
try (
OutputStream os = new FileOutputStream(name); ) {

//INSERT CODE HERE

//flush and close the streams that are open
}

}

Which of the following combinations of the lines of code and their outcome when inserted above, are correct?

You had to select 2 option(s)

Q6. Consider the following program :

class Test{
public static void main(String[] args){
short s = 10; // 1
char c = s; // 2
s = c; // 3
}
}

Identify the correct statements.

You had to select 2 option(s)

Q7. What will be the result of attempting to compile and run the following program?

public class TestClass{
public static void main(String args[ ] ){
String s = "hello";
StringBuilder sb = new StringBuilder( "hello" );
sb.reverse();
s.reverse();
if( s == sb.toString() ) System.out.println( "Equal" );
else System.out.println( "Not Equal" );
}
}

You had to select 1 option(s)

Q8. Consider the following program:

import java.util.*;
public class TestClass
{
static String[] sa = { "a", "aa", "aaa", "aaaa" };
static
{
Arrays.sort(sa);
}
public static void main(String[] args)
{
String search = "";
if(args.length != 0) search = args[0];
System.out.println(Arrays.binarySearch(sa, search));
}
}

What are all possible values this program can print when run?

You had to select 1 option(s)

Q9. Given the following code:

class M { }
class N{
private M m = new M();
public void makeItNull(M pM){
pM = null;
}
public void makeThisNull(){
makeItNull(m);
}
public static void main(String[] args){
N n = new N();
n.makeThisNull();
}
}

Which of the following statements are correct?

You had to select 1 option(s)

Q10. Given:

public class FunWithArgs {
public static void main(String[][] args) {
System.out.println(args[0][1]);
}
public static void main(String[] args) {
var fwa = new FunWithArgs();
String[][] newargs = {args};
fwa.main(newargs);
}
}

The above program is compiled with the command line:
javac FunWithArgs.java
and then run with:
java FunWithArgs a b c

What will be the output?

You had to select 1 option(s)

Q11. Identify the correct statements about the following code:

import java.util.*;
class Person {
private String name;
public Person(String name) { this.name = name; }
public String getName() { return name; }
public void setName(String name) { this.name = name; }

public String toString() { return name; }
}

class Helper {

public void helpPeople(Queue people, Queue helped) {
do {
Person p = (Person) people.poll();
System.out.println("Helped : " + p + " ");
helped.offer(p.getName());
} while (!people.isEmpty());
}

public static void main(String[] args) {
Queue q = new LinkedList();
q.offer(new Person("Pope"));
q.offer(new Person("John"));
Queue helpedQ = new LinkedList();
Helper h = new Helper();
h.helpPeople(q, helpedQ);
}
}

You had to select 2 option(s)

Q12. Consider the following code:

import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;
public class MyCache {
private CopyOnWriteArrayList cal = new CopyOnWriteArrayList();

public void addData(List list){
cal.addAll(list);
}

public int getCacheSize(){
return cal.size();
}
}

Given that one thread calls the addData method on an instance of the above class with a List containing 10 Strings and another thread calls the getCacheSize method on the same instance at the same time, which of the following options are correct?

(Assume that no other calls have been made on the MyCache instance.)

You had to select 1 option(s)

Q13. Given:

sealed class Automobile permits Car, Bus{
}
final class Car extends Automobile{
}
final class Bus extends Automobile{
}


What can be inserted in the following method code?

public static Automobile getSomething(){
final int x = 1;
return switch(x){
case 0 -> new Car();

INSERT CODE HERE

};
}

You had to select 2 option(s)

Q14. What can be inserted in the following code so that it will print exactly 2345 when compiled and run?

public class FlowTest {

static int[] data = {1, 2, 3, 4, 5};

public static void main(String[] args) {
for (var i : data) {
if (i < 2) {
//insert code1 here
}
System.out.print(i);
if (i == 3) {
//insert code2 here
}
}
}
}

You had to select 2 option(s)

Q15. What will the following code print when compiled and run?

BiPredicate bip = (s, i)-> s.length()>i; //1
BiFunction bif = (s, i)-> { //2
if(bip.test(s, i)){ //3
return s.substring(0, i);
}
else return s;
};
String str = bif.apply("hello world", 5); //4
System.out.println(str);

You had to select 1 option(s)

Q16. Given the following classes and declarations, which of these statements about //1 and //2 are true?

class A{
private int i = 10;
public void f(){}
public void g(){}
}

class B extends A{
public int i = 20;
public void g(){}
}

public class C{
A a = new A();//1
A b = new B();//2
}

You had to select 1 option(s)

Q17. What will be the output when the following class is compiled and run?

class ScopeTest{
static int x = 5;
public static void main(String[] args){
int x = ( x=3 ) * 4; // 1
System.out.println(x);
}
}

You had to select 1 option(s)

Q18. Given:

public class TestClass {
static int count = 0;

public static void main(String[] args) throws Exception{
ExecutorService es = Executors.newFixedThreadPool(5);
for(int i=0; i<5; i++){
es.submit( () ->
{
for(int j=0; j<5000; j++){
TestClass.count++;
}
}
);
}
es.awaitTermination(10, TimeUnit.SECONDS);
es.shutdownNow();
System.out.println(count);
}

}

Identify correct statement(s) about the above code.

You had to select 2 option(s)

Q19. What will the following code print?

var a = new int[]{ 1, 2, 3, 4, 5};
var b = new int[]{ 1, 2, 3, 4, 5, 3};
var c = new int[]{ 1, 2, 3, 4, 5, 6};

int x = Arrays.compare(a, c);
int y = Arrays.compare(b, c);
System.out.println(x+" "+y);

You had to select 1 option(s)

Q20. Given:

String sentence1 = "Carpe diem. Seize the day, boys. Make your lives extraordinary.";
String sentence2 = "Frankly, my dear, I don't give a damn!";
String sentence3 = "Do I look like I give a damn?";
List sentences = Arrays.asList(sentence1, sentence2, sentence3);

Which of the following options will create a stream containing all the words in the three sentences without repetition?

You had to select 1 option(s)

Q21. Given:

List l1 = Arrays.asList("a", "b");
List l2 = Arrays.asList("1", "2");

Which of the following lines of code will print the following output?
a
b
1
2

You had to select 1 option(s)

Q22. Consider the following code in which searchBook() method has an inner class.

public class BookStore
{
private static final int taxId = 300000;
private String name;
public String searchBook( final String criteria )
{
int count = 0;
int sum = 0;
sum++;
class Enumerator
{
String iterate( int k)
{
//line 1
return "";
}
// lots of code.....
}
// lots of code.....
return "";
}
}

Which variables are accessible at line 1?

You had to select 5 option(s)

Q23. Given that Daylight Savings Time ends on Nov 1 at 2 AM in US/Eastern time zone, what will the following code print -

LocalDateTime ld = LocalDateTime.of(2022, Month.OCTOBER, 31, 10, 0);

ZonedDateTime date = ZonedDateTime.of(ld, ZoneId.of("US/Eastern"));
date = date.plus(Duration.ofDays(1));
System.out.println(date);

date = ZonedDateTime.of(ld, ZoneId.of("US/Eastern"));
date = date.plus(Period.ofDays(1));
System.out.println(date);

You had to select 1 option(s)

Q24. What is wrong with the following code?

class MyException extends Exception {}
public class TestClass{
public static void main(String[] args){
TestClass tc = new TestClass();
try{
tc.m1();
}
catch (MyException e){
tc.m1();
}
finally{
tc.m2();
}
}
public void m1() throws MyException{
throw new MyException();
}
public void m2() throws RuntimeException{
throw new NullPointerException();
}
}

You had to select 1 option(s)

Q25. Which statement regarding the following code is correct?

class A{
public int i = 10;
private int j = 20;

}

class B extends A{
private int i = 30; //1
public int k = 40;

}

class C extends B{
}

public class TestClass{
public static void main(String args[]){
C c = new C();
System.out.println(c.i); //2
System.out.println(c.j); //3
System.out.println(c.k);
}
}

You had to select 1 option(s)

Q26. Given:

You are trying to initialize the STOCK table and for that you need to insert one row for each of the ticker value in the tickers array. Each row has to be initialized with the same values except the ID and TICKER columns, which are different for each row. The ID column is defined as AUTO_INCREMENT and so you need to pass only 0 for this column.

Which of the following code snippets would you use?

You had to select 1 option(s)

Q27. Given:

class MyException extends Exception {
private final int code;
public MyException(int code, Throwable actualEx){
super(actualEx);
this.code = code;
}

public MyException(int code, String message, Throwable actualEx){
super(message, actualEx);//1
this.code = code;
}

public String getMessage(){
return String.format("Exception - Code=%d, Msg=%s, OrigMsg=%s", code,
super.getMessage(), this.getCause().getMessage()); //2
}
}

public class TestClass {
public static void main(String[] args) {
try{
throw new MyException(new IOException("NOT FOUND")); //3
}catch(Exception e){
System.out.println(e.getMessage());
}
}
}

What is the result?

You had to select 1 option(s)

Q28. Given the following two files in /user/home directory:

In file messages.properties:
message=hi {0}, thanks {1}

In file messages_fr_FR.properties:
message=salut {0}, merci {1}

and the following class in /user/home directory:

public class TestClass
{
public static void main(String[] args) {

//INSERT CODE HERE
System.out.println(message);
}
}


Which of the following options when inserted in TestClass will print salut Amy, merci Adams?
Answered Incorrectly

You had to select 2 option(s)

Q29. Given:

public static void reader(String fileName1) throws Exception{
try (var fr = new FileReader(fileName1);) {
int charRead = 0;
while ((charRead = fr.read()) != -1) {
System.out.println("Read char " + charRead);
}
}
}

What can be done to the above code to make it read Strings instead of chars?

You had to select 1 option(s)

Q30. Given:

List letters = Arrays.asList("j", "a", "v","a");
Which of the following code snippets will print JAVA?

You had to select 3 option(s)

Q31. Which of these array declarations and instantiations are legal?

You had to select 4 option(s)

Q32. Given the following class, which of the given blocks can be inserted at line 1 without errors?

public class InitClass{
private static int loop = 15 ;
static final int INTERVAL = 10 ;
boolean flag ;
//line 1
}

You had to select 4 option(s)

Q33. Assume the following declarations:

class A{ }
class B extends A{ }
class C extends B{ }

class X{
B getB(){ return new B(); }
}

class Y extends X{
//method declaration here
}

Which of the following methods can be inserted in class Y?

You had to select 2 option(s)

Q34. What will the following code print?

void crazyLoop(){
var c = 0;
JACK: while (c < 8){
JILL: System.out.println(c);
if (c > 3) break JILL; else c++;
}
}

You had to select 1 option(s)

Q35. Consider the following classes :

interface I{
}

class A implements I{
}

class B extends A {
}

class C extends B{
}
And the following declarations:
A a = new A();
B b = new B();

Identify options that will compile and run without error.

You had to select 1 option(s)

Q36. Given:

class TestClass{
public static void main(String[] args) throws IOException {

final InputStream fis = new FileInputStream("c:\\temp\\test.txt");
long l = 0;
try(fis){
l = fis.read();//1
}finally{
l = fis.read();//2
}
l = fis.read();//3
System.out.println(l);//4
}
}

Assuming that c:\\temp\\test.txt is readable, what will be the output?

You had to select 1 option(s)

Q37. Given:

Map hm = new ConcurrentHashMap();
hm.put(null, "asdf"); //1
hm.put("aaa", null); //2

hm = new HashMap();
hm.put(null, "asdf"); //3
hm.put("aaa", null); //4

List list = new ArrayList();
list.add(null); //5
list.add(null); //6

list = new CopyOnWriteArrayList();
list.add(null); //7


Which of the above lines will throw NullPointerException?
(Assume that each of the put and add calls are executed as if they are wrapped inside a try/catch block i.e. an exception thrown at //1 will not prevent the execution of //2.)

You had to select 2 option(s)

Q38. Given:

class M {
static Object obj = null;
public M(String val){ obj = val; }
}

class N{

private M m = new M("hello");

public static void main(String[] args){
N n = new N();
n = null;
System.gc();
System.out.println(M.obj);
}
}

Assuming that System.gc() does its job, what will be printed?

You had to select 1 option(s)

Q39. Given the following class:

public class Food{ // LINE 1
String name;
int caloriesPerServing;
public Food(String name, int calories){
this.name = name; this.caloriesPerServing = calories;
}
//accessors not shown

//LINE 2
}

This class is used in an application as follows -

ArrayList al = new ArrayList();
//code that adds Food objects to al not shown
Collections.sort(al);

What changes must be done to Food class so that the call to Collections.sort(al) will work as expected?

You had to select 2 option(s)

Q40. Given:

List primes = Arrays.asList(2, 3, 5, 7, 11, 13, 17); //1
Stream primeStream = primes.stream(); //2

Predicate test1 = k->k<10; //3
long count1 = primeStream.filter(test1).count();//4

Predicate test2 = k->k>10; //5
long count2 = primeStream.filter(test2).count(); //6

System.out.println(count1+" "+count2); //7


Identify correct statements.

You had to select 1 option(s)

Q41. Consider the following classes :

class A{
public static void sM1() { System.out.println("In base static"); }
}

class B extends A{

Line 1 --> // public static void sM1() { System.out.println("In sub static"); }

Line 2 --> // public void sM1() { System.out.println("In sub non-static"); }

}

Which of the following statements are true?

You had to select 2 option(s)

Q42. Given:

class MyProcessor{
int value;
public MyProcessor(){ value = 10; }
public MyProcessor(int value){
this.value = value;
}
public void process(){
System.out.println("Processing "+value);
}
}

Which of the following code snippets will print Processing 10?

You had to select 2 option(s)

Q42. Which of the following are valid JDBC URLs?

You had to select 1 option(s)

Q43. Which of these for statements are valid when present in a method?

1. for (var i=5; i=0; i--) { }

2. var j=5;
for(int i=0, j+=5; i
3. int i, j;
for (j=10; i
4. var i=10;
for ( ; i>0 ; i--) { }

5. for (int i=0, j=10; i
6. for (var i=0, j=10; i
You had to select 1 option(s)

Q45. Consider the following interface definition:

Q46. What will the following code print when run?

class A{
String value = "test";
A(String val){
this.value = val;
}
}
public class TestClass {
public static void main(String[] args) throws Exception {
new A("new test").print();
}
}

You had to select 1 option(s)

Q47. Consider the following code:

class OuterWorld
{
public InnerPeace i = new InnerPeace("none"); //1
class InnerPeace
{
private String reason = "none";
InnerPeace(String reason){ this.reason = reason; }
}
public static void main(String[] args){
var ip = new InnerPeace("yoga"); //2
var out = new OuterWorld();
System.out.println(out.i.reason); //3
}
}

Identify correct statements about the above code.

You had to select 2 option(s)

Q48. Consider these two interfaces:

interface I1
{
void m1() throws java.io.IOException;
}
interface I2
{
void m1() throws java.io.FileNotFoundException;
}

Which of the following are valid method declarations for a class that says it implements I1 and I2 ?

You had to select 1 option(s)

Q49. Identify the correct statements about the following code:

import java.util.*;
class Person {
private static int count = 0;
private String id = "0"; private String interest;
public Person(String interest){ this.interest = interest; this.id = "" + ++count; }
public String getInterest(){ return interest; }
public void setInterest(String interest){ this.interest = interest; }
public String toString(){ return id; }
}

public class StudyGroup
{
String name = "MATH";
TreeSet set = new TreeSet();
public void add(Person p) {
if(name.equals(p.getInterest())) set.add(p);
}

public static void main(String[] args) {
StudyGroup mathGroup = new StudyGroup();
mathGroup.add(new Person("MATH"));
System.out.println("A");
mathGroup.add(new Person("MATH"));
System.out.println("B");
System.out.println(mathGroup.set);
}
}

You had to select 1 option(s)

Q50. Consider the following code:

//INSERT CODE HERE
a[0][0] = 1;
a[0][1] = 2;


a[1][0] = 3;
a[1][1] = 4;
a[1][2] = 5;
a[1][3] = 6;
What can be inserted independently in the above code so that it will compile and run without any error or exception?

You had to select 2 option(s)