Standard Unique Test 4-Java SE 21 Developer  exam 1Z0-830

Practice Test 26 continues the Free Java SE 21 Developer Professional certification exam 1Z0-830 practice tests for candidates looking at high-growth product companies. Those teams still need Java developers even when public conversation focuses on other languages. Enterprise-scale services and customer backends do not get rewritten every year. Employers hire people who can work inside what already runs. Growth companies still ask whether you can work in an existing system, which is why the credential and a project both matter.

Certification benefits help you get considered. Job offers in Java reward a current credential plus the ability to talk about what you built. Java is the language of choice for enterprise companies, and it remains widely used in product engineering too. Uber, Airbnb, and Spotify hire Java developers for large services. Use this free test as a readiness check, not as a substitute for projects and interviews.

SynergisticIT JOPP helps jobseekers get certified, prepared, and hired at top tech companies through our Job Placement programs — Java DevOps Full Stack JOPP and Data Science JOPP.

If you want to get hired as a software developer, contact SynergisticIT at the contact us page and review SynergisticIT JOPP.

Welcome to your Standard Tests - Unique Test 4 : 2025

Name

Email

Phone

Q1. What happens when you try to compile and run the following program?

public class CastTest{
public static void main(String args[ ] ){
byte b = -128 ;
int i = b ;
b = (byte) i;
System.out.println(i+" "+b);
}
}

Select 1 option(s):

The compiler will refuse to compile it because i and b are of different types cannot be assigned to each other.

The program will compile and will print -128 and -128 when run .

The compiler will refuse to compile it because -128 is outside the range of values for a byte.

The program will compile and will print 128 and -128 when run .

The program will compile and will print 255 and -128 when run .

None

Q2. Given that the test directory contains two files as described below:

File values1.txt contains:
#13
241
35

File values2.txt contains:
23
#50
12

What will be the output of the following code :

Integer sum = Files.list(Path.of("c:\\temp\\test"))
.flatMap( p -> { try{ return Files.lines(p);
}catch(IOException e){
return null;
} } )
.filter(line -> !line.startsWith("#"))
.map(line -> Integer.parseInt(line.substring(1)))
.reduce((i1, i2)->i1+i2)
.get();
System.out.println(sum);

Select 1 option(s):

51

3

0

6

14

63

An exception will be thrown at run time.

None

Q3. Given:

class A extends Thread
{
public void run()
{
System.out.println("Starting loop");
try{
Thread.sleep(10000); //1 sleep for 10 secs
}catch(Exception e){ e.printStackTrace(); }
System.out.println("Ending loop");
}
}
public class TestClass
{
public static void main(String args[]) throws Exception
{
A a = new A();
a.start();
Thread.sleep(100);
a.interrupt();
}
}

What will be the states of the main thread and the "A" thread created in the above program after the main thread calls a.interrupt()?

Select 1 option(s):

main thread: RUNNABLE
A thread: RUNNABLE

main thread: RUNNABLE
A thread: TERMINATED

main thread: BLOCKED
A thread: RUNNABLE

main thread: WAITING
A thread: TERMINATED

main thread: RUNNABLE
A thread: WAITING

None

Q4. What should be placed in the two blanks so that the following code will compile without errors:

class XXX{
public void m() {
throw new RuntimeException();
}
}
class YYY extends XXX{
public void m() throws Exception{
throw new Exception();
}
}
public class TestClass {
public static void main(String[] args) {
______ obj = new ______();
obj.m();
}
}

Select 1 option(s):

XXX and YYY

XXX and XXX

YYY and YYY

YYY and XXX

None of the options will make the code compile.

None

Q5. Assuming that the following method will always be called with a phone number in the format ddd-ddd-dddd (where d stands for a digit), what can be inserted at //1 so that it will return a String containing "xxx-xxx-"+dddd, where dddd represents the same four digits in the original number?

public static String hidePhone(String fullPhoneNumber){
//1 Insert code here
}

Select 2 option(s):

String mask = "xxx-xxx-";
mask.append(fullPhoneNumber.substring(8));
return mask;

return new StringBuilder("xxx-xxx-")+fullPhoneNumber.substring(8);

return new StringBuilder(fullPhoneNumber).replace(0, 7, "xxx-xxx-").toString();

return "xxx-xxx-"+fullPhoneNumber.substring(8, 12);

Q6. Given the following code:

//in WeekDay.java
package days;
public sealed class WeekDay permits Monday {
}

Which of the following is a valid declaration of Monday?

Select 1 option(s):

package calendar;
final class Monday extends WeekDay{
}

package days;
final class Monday {
}

package days;
class Monday extends WeekDay{
}

package days;
non-sealed class Monday extends WeekDay{
}

package days;
sealed class Monday extends WeekDay{
}

None

Q7. Given:

//assume appropriate imports
public class Calculator{
public static void main(String[] args) {
double principle = 100;
int interestrate = 5;
double amount = compute(principle, x->x*interestrate);
}

INSERT CODE HERE
}

Which of the following methods can be inserted in the above code so that it will compile and run without any error/exception?

Select 2 option(s):

public static double compute(double base, Function<Integer, Integer > func){
return func.apply((int)base);
}

public static double compute(double base, Function<Integer, Double> func){
return func.apply((int)base);
}

public static double compute(double base, Function<Double, Integer> func){
return func.apply(base);
}

public static double compute(double base, Function<Double, Double> func){
return func.apply(base);
}

public static double compute(double base, Function<Integer, Double> func){
return func.apply(base);
}

Q8. Given:

Locale locale = new Locale("en", "US");
ResourceBundle rb = ResourceBundle.getBundle("test.MyBundle", locale);

Which of the following are valid lines of code?
(Assume that the ResourceBundle has the values for the given keys.)

Select 2 option(s):

String obj = rb.getObject("key1");

Object obj = rb.getObject("key1");

String[] vals = rb.getStringArray("key2");

Object obj = rb.getValue("key3");

Object obj = rb.getObject(1);

Q9. Identify correct statements about the modular system of Java.

Select 3 option(s):

A module can allow other modules to access all its types and members of its type through reflection.

By default, a module exhibits strong encapsulation by preventing reflective access to it types.

A module can be used by non-modular code by putting that module on the classpath.

An application can either use module-path or classpath but not both.

A sealed class belonging to a module may list classes belonging to other modules in its permits clause.

Q10. What will be the result of attempting to compile and run the following class?

public class InitTest{
static String s1 = sM1("a");{
s1 = sM1("b");
}
static{
s1 = sM1("c");
}
public static void main(String args[]){
InitTest it = new InitTest();
}
private static String sM1(String s){
System.out.println(s); return s;
}
}

Select 1 option(s):

The program will fail to compile.

The program will compile without error and will print a, c and b in that order when run.

The program will compile without error and will print a, b and c in that order when run.

The program will compile without error and will print c, a and b in that order when run.

The program will compile without error and will print b, c and a in that order when run.

None

Q11. Given:

public static void copy1(Path p1, Path p2) throws Exception {
Files.copy(p1, p2, StandardCopyOption.REPLACE_EXISTING);
}

Identify correct statements.

Select 2 option(s):

An exception will be thrown at runtime if p2 is a symbolic link.

If p2 is a symbolic link, then that link, and not the target of that link, will be replaced .

If p1 is a symbolic link, then the final target of the link is copied to p2.

An exception will be thrown at runtime if either of p1 or p2 is a symbolic link.

Result is OS dependent if either of p1 or p2 is a symbolic link.

Q12. What will the following line of code print?

System.out.println(LocalDate.of(2022, Month.JANUARY, 01)
.format(DateTimeFormatter.ISO_DATE_TIME));

Select 1 option(s):

01 Jan 2022

01 January 2022 00:00:00

2022-01-01

2022-01-01T00:00:00

Exception at run time.

None

Q13. Consider the following code:

class Account{
private String id; private double balance;

ReentrantLock lock = new ReentrantLock();

public void withdraw(double amt){
try{
lock.lock();
if(balance > amt) balance = balance - amt;
}finally{
lock.unlock();
}
}
}

What can be done to make the above code thread safe?

Select 1 option(s):

Change new ReentrantLock() to new ReentrantLock(true).

Move the call to lock.lock(); to before the try block.

Declare lock variable as private and final.

Make the lock variable private, final, and static.

Make the lock variable static.

No change is required.

None

Q14. Given the following code:

package com.auto.vehicles;
public interface Drivable{
void drive();
}

and

package com.auto.vehicles.electric;
public class ECar implements Drivable{
private int maxSpeed;
public ECar(){
this(120);
}
public ECar(int maxSpeed){
this.maxSpeed = maxSpeed;
}

@Override
public void drive(){
System.out.println("driving ecar");
}
}

Which statements should be present in the module-info for it to represent a service provider?

Select 2 option(s):

requires com.auto.vehicles.Drivable;

requires com.auto.vehicles.electric.ECar;

exports com.auto.vehicles.Drivable;

exports com.auto.vehicles;

provides com.auto.vehicles.Drivable;

provides com.auto.vehicles.Drivable to com.auto.vehicles.electric;

provides com.auto.vehicles.Drivable with com.auto.vehicles.electric.ECar;

provides com.auto.vehicles.electric.ECar;

Q15. Consider the following class...

public class ParamTest {

public static void printSum(double a, double b){
System.out.println("In double "+(a+b));
}

public static void printSum(float a, float b){
System.out.println("In float "+(a+b));
}

public static void main(String[] args) {
printSum(1, 2.0);
printSum(1, 2);
printSum(1.0, 2.0);
}
}

What will be printed?

Select 1 option(s):

In float 3.0
In float 3.0
In float 3.0

In double 3.0
In double 3.0
In double 3.0

In double 3.0
In float 3.0
In double 3.0

In float 3.0
In double 3.0
In float 3.0

It will not compile.

None

Q16. What will the following code print?

String s = "blooper";
StringBuilder sb = new StringBuilder(s);
sb.append(s.substring(4)).delete(3, 5);
System.out.println(sb);

Select 1 option(s):

blorbloo

bloper

bloerper

blooperper

bloo

None

Q17. Given:

public class CrazyMath {
public static void main(String[] args) {
int x = 10, y = 20;
int dx, dy;
try{
dx = x % 5;
dy = y/dx;
}catch(ArithmeticException ae){
System.out.println("Caught AE");
dx = 2;
dy = y/dx;
}
x = x/dx;
y = y/dy;
System.out.println(dx+" "+dy);
System.out.println(x+" "+y);

}
}

What is the output?

Select 1 option(s):

Caught AE
2 10
5 5

Caught AE
2 10
5 2

2 10
5 2

It will not compile.

None

Q18. Which of the following method implementations will write a boolean value to the underlying stream?

Select 3 option(s):

public void usePrintWriter(PrintWriter pw){
boolean bval = true;
pw.writeBoolean(bval);
}

public void usePrintWriter(PrintWriter pw) throws IOException{
boolean bval = true;
pw.write(bval);
}

public void usePrintWriter(PrintWriter pw) throws IOException{
boolean bval = true;
pw.print(bval);
}

public void usePrintWriter(PrintWriter pw) {
boolean bval = true;
pw.print(bval);
}

public void usePrintWriter(PrintWriter pw) {
boolean bval = true;
pw.println(bval);
}

Q19. What can be done to get the following code to compile and run? (Assume that the options are independent of each other.)

public float parseFloat( String s ){
float f = 0.0f; // 1
try{
f = Float.valueOf( s ).floatValue(); // 2
return f ; // 3
}
catch(NumberFormatException nfe){
f = Float.NaN ; // 4
return f; // 5
}
finally {
return f; // 6
}
return f ; // 7
}

Select 4 option(s):

Remove line 3, 6

Remove line 5

Remove line 5, 6

Remove line 7

Remove line 3, 7

Q20. Consider the following code:

import java.util.*;
class Book{ }
class TextBook extends Book{ }

class BookList extends ArrayList
{
public int count = 0;
public boolean add(Object o)
{
if(o instanceof Book b) return super.add(b);
else return count++ == -1;
}
}

//in valid context
BookList list = new BookList();
list.add(new Book());
list.add(new TextBook());
list.add("hello");

System.out.println(list.count);

What will it print?

Select 1 option(s):

0

1

2

It will not compile because the add method does not correctly override the add method from ArrayList.

It will not compile because on incorrect usage of instanceof.

It will throw an exception at runtime.

None

Q21. The following code was written for Java 7:

Map<String, List> groupedValues = new HashMap();

public void process(String name, Double value){
List values = groupedValues.get(name);
if(values == null){
values = new ArrayList();
groupedValues.put(name, values);
}
values.add(value);
}

Which of the following implementations correctly makes use of the functional interfaces available in the Java standard library to achieve the same?

Select 1 option(s):

public void process(String name, Double value){
groupedValues.computeIfAbsent(name, (a)->new ArrayList< Double >()).add(value);
}

public void process(String name, Double value){
groupedValues.computeIfAbsent(name, (a, b)->new ArrayList< Double >()).add(value);
}

public void process(String name, Double value){
groupedValues.computeIfPresent(name, (a, b)->new ArrayList< Double >()).add(value);
}

public void process(String name, Double value){
groupedValues.compute(name, (a)->new ArrayList< Double >()).add(value);
}

None

Q22. Given:

module broker{
exports org.broker.api;
provides org.broker.api.Broker with org.broker.api.MyBroker
}

Which of the following statements are correct?

Select 3 option(s):

This is not a valid service definition module because it provides the service instead of defining it.

This is not a valid service provider module because it does not contain appropriate requires clause for service definition.

Other modules can also provide implementations for org.broker.api.Broker service.

Placing the org.broker.api package in a separate module named brokerapi would make it easy to install multiple provider modules.

It is not a good idea to include MyBroker and Broker in the same module because that allows the user of the service to inadvertantly depend on the implementation class.

Q23. Consider the following hierarchy of Exception classes :

java.lang.RuntimeException
+----- IndexOutOfBoundsException
+----ArrayIndexOutOfBoundsException, StringIndexOutOfBoundsException

Which of the following statements are correct for a method that can throw ArrayIndexOutOfBounds as well as StringIndexOutOfBounds Exceptions but does not have try catch blocks to catch the same?

Select 3 option(s):

The method calling this method will either have to catch these 2 exceptions or declare them in its throws clause.

It is ok if it declares just throws ArrayIndexOutOfBoundsException

It must declare throws ArrayIndexOutOfBoundsException, StringIndexOutOfBoundsException

It is ok if it declares just throws IndexOutOfBoundsException

It does not need to declare any throws clause.

Q24. A modularized application has been packaged in graphs.jar file with module name as com.xcomp.graphs. The entry point of the application is a class named Main in package com.xcomp.graphs.

Which two options can be used to execute this application?

Select 2 option(s):

java --module-path graphs.jar --module com.xcomp.graphs.Main

java --module-path graphs.jar --module com.xcomp.graphs/com.xcomp.graphs.Main

java -classpath graphs.jar --module com.xcomp.graphs/com.xcomp.graphs.Main

java --module-path graphs.jar com.xcomp.graphs.Main

java -classpath graphs.jar com.xcomp.graphs.Main

java --module-path graphs.jar --main-class com.xcomp.graphs.Main

Q25. Identify correct statements about the following code -

interface Drink{
default double getAlcoholPercent(){
return 0.0;
}

static double computeAlcoholPercent(){
return 0.0;
}
}


interface ColdDrink extends Drink{
String getName();
}

class CrazyDrink implements ColdDrink{
// INSERT CODE HERE
}

Select 1 option(s):

CrazyDrink must either implement getName or be marked abstract.

CrazyDrink must either implement getName as well as computeAlcoholPercent or be marked abstract.

CrazyDrink must either implement getName as well as getAlcoholPercent or be marked abstract.

CrazyDrink must either implement getName or be marked abstract. Further, computeAlcoholPercent must be removed from Drink.

None

Q26. What will the following code print?

Object v1 = IntStream.rangeClosed(10, 15)
.boxed()
.filter(x->x>12)
.parallel()
.findAny();

Object v2 = IntStream.rangeClosed(10, 15)
.boxed()
.filter(x->x>12)
.sequential()
.findAny();

System.out.println(v1+":"+v2);

(Note: in the options below denote the possible output and not the sign themselves.)

Select 1 option(s):

Optional[13]:Optional[13]

< An Optional containing 13, 14, or 15 >:Optional[13]

< An Optional containing 13, 14, or 15 >:< An Optional containing 13, 14, or 15 >

14:13

< 13, 14, or 15 >:13

< 13, 14, or 15 >:< 13, 14, or 15 >

An exception at run time.

None

Q27. Given the following code :

public class TestClass {

int[][] matrix = new int[2][3];

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

public int compute(int x, int y){
//1 : Insert Line of Code here
}

public void loadMatrix(){
for(int x=0; x<matrix.length; x++){
for(int y=0; y<matrix[x].length; y++){
//2: Insert Line of Code here
}
}
}
}

What can be inserted at //1 and //2?

Select 1 option(s):

return a(x)*b(y);
and
matrix(x, y) = compute(x, y);

return a[x]*b[y];
and
matrix[x, y] = compute(x, y);

return a[x]*b[y];
and
matrix[x][y] = compute(x, y);

return a(x)*b(y);
and
matrix(x)(y) = compute(x, y);

return a[x]*b[y];
and
matrix[[x][y]] = compute(x, y);

None

Q28. What will the following code print when run without any arguments ...

public class TestClass {

public static int m1(int i){
return ++i;
}

public static void main(String[] args) {

int k = m1(args.length);
k += 3 + ++k;
System.out.println(k);
}

}

Select 1 option(s):

It will throw ArrayIndexOutOfBoundsException.

It will throw NullPointerException.

6

5

7

2

None of these.

None

Q29. What will the following program print?

public class TestClass{
static int someInt = 10;
public static void changeIt(int a){
a = 20;
}
public static void main(String[] args){
changeIt(someInt);
System.out.println(someInt);
}
}

Select 1 option(s):

10

20

It will not compile.

It will throw an exception at runtime.

None of the above.

None

Q30. Given:

public class ItemProcessor implements Runnable{ //LINE 1
CyclicBarrier cb;
public ItemProcessor(CyclicBarrier cb){
this.cb = cb;
}
public void run(){
System.out.println("processed");
try {
cb.await();
} catch (Exception ex) {
ex.printStackTrace();
}
}
}

public class Merger implements Runnable{ //LINE 2
public void run(){
System.out.println("Value Merged");
}
}

What should be inserted in the following code such that run method of Merger will be executed only after the thread started at 4 and the main thread have both invoked await?

public static void main(String[] args) throws Exception{
var m = new Merger();

//LINE 3

var ip = new ItemProcessor(cb);
ip.start(); //LINE 4
cb.await();
}

Select 1 option(s):

Make ItemProcessor extend Thread instead of implementing Runnable and add CyclicBarrier cb = new CyclicBarrier(1, m); to //LINE 3

Make ItemProcessor extend Thread instead of implementing Runnable and add CyclicBarrier cb = new CyclicBarrier(2, m); to //LINE 3

Make Merger extend Thread instead of implementing Runnable and add CyclicBarrier cb = new CyclicBarrier(1, m); to //LINE 3

Make Merger extend Thread instead of implementing Runnable and add CyclicBarrier cb = new CyclicBarrier(2, m); to //LINE 3

Just add CyclicBarrier cb = new CyclicBarrier(1, m); to //LINE 3

Just add CyclicBarrier cb = new CyclicBarrier(2, m); to //LINE 3

None

Q31. What will the following code print when run?

String[] sa = { "charlie", "bob", "andy", "dave" };
Collections.sort(Arrays.asList(sa), null);
System.out.println(sa[0]);

Select 1 option(s):

charlie

andy

dave

It will throw a NullPointerException

It will not compile.

None

Q32. What will the following code print when compiled and run:

public class TestClass {

public static void main(String[] args){
while(var k = 5; k<7){
System.out.println(k++);
}
}
}

Select 1 option(s):

5
6

5
6
7

It will keep printing 5.

It will not compile.

It will throw an exception at run time.

None

Q33. Given:

int[][] iaa = { {1, 2}, {3, 4}, { 5, 6} };
long count = Stream.of(iaa).flatMapToInt(IntStream::of)
.map(i->i+1).filter(i->i%2 != 0).peek(System.out::print).count();
System.out.println(count);

What will be the output?

Select 1 option(s):

3573

2463

3

2345676

None

Q34. What will be the result of compiling and running the following code:

float foo = 2, bar = 3, baz = 4; //1
float mod1 = foo % baz, mod2 = baz % foo; //2
float val = mod1>mod2? bar : baz; //3
System.out.println(val);

Select 1 option(s):

Compilation error at //1

Compilation error at //2

Compilation error at //3

3

3.0

3.0f

4

4.0

4.0f

None

Q35. Given the following code:

Locale.setDefault(Locale.ITALY);
Locale loc = new Locale.Builder().setLanguage("en").build();
ResourceBundle rb = ResourceBundle.getBundle("mymsgs", loc);
System.out.println(rb.getString("helloMsg"));

and the following properties files:
mymsgs.properties
mymsgs_en_IT.properties
mymsgs_en.properties
mymsgs_IT.properties

Which of the following statements are correct?

Select 2 option(s):

If helloMsg is defined in all the four properties files, the value from mymsgs_en.properties will be displayed.

If helloMsg is defined in all the four properties files, the value from mymsgs_en_IT.properties will be displayed.

If helloMsg is defined only in mymsgs_IT.properties, then that value will be displayed.

If helloMsg is not defined in mymsgs_en.properties file but is defned in mymsgs.properties and mymsgs_en_IT.properties, then the value from mymsgs.properties will be displayed.

A java.util.MissingResourceException will be NOT be thrown if helloMsg is defined in any one of the given four properties files.

Q36. Given:

public class Book {
private String title;
private String genre;
public Book(String title, String genre){
this.title = title; this.genre = genre;
}
//accessors not shown
}

and the following code:

List books = List.of(
new Book("Gone with the wind", "Fiction"),
new Book("Bourne Ultimatum", "Thriller"),
new Book("The Client", "Thriller")
);

Reader r = b->{
System.out.println("Reading book "+b.getTitle());
};
books.forEach(x->r.read(x));

What would be a valid definition of Reader for the above code to compile and run without any error or exception?

Select 2 option(s):

abstract class Reader{
abstract void read(Book b);
}

abstract class Reader{
void read(Book b);
}

interface Reader{
void read(Book b);
default void unread(Book b){ }
}

interface Reader{
default void read(Book b){ }
void unread(Book b);
}

interface Reader{
default void read(Book b){ System.out.println("Default read");};
}

Q37. Which of the following code fragments compile without any error?

Select 3 option(s):

for(;Math.random()<0.5;){
System.out.println("true");
}

for(;;Math.random()<0.5){
System.out.println("true");
}

for(;;Math.random()){
System.out.println("true");
}

for(;;){
Math.random()<.05? break : continue;
}

for(;;){
if(Math.random()<.05) break;
}

Q38. Consider the following code:

class Base{
private float f = 1.0f;
void setF(float f1){ this.f = f1; }
}
class Base2 extends Base{
private float f = 2.0f;
//1
}

Which of the following options is/are valid example(s) of overriding?

Select 2 option(s):

protected void setF(float f1){ this.f = 2*f1; }

public void setF(double f1){ this.f = (float) ( 2*f1); }

public void setF(float f1){ this.f = 2*f1; }

private void setF(float f1){ this.f = 2*f1; }

float setF(float f1){ this.f = 2*f1; return f;}

Q39. Given:

Stream strm1 = Stream.of(2, 3, 5, 7, 11, 13, 17, 19); //1
Stream strm2 = strm1.filter(i->{ return i>5 && i<15; }); //2
strm2.forEach(System.out::print); //3

Which of the following options can be used to replace line at //2 and still print the same elements of the stream?

Select 1 option(s):

Stream< Integer > strm2 = strm1.filter(i>5).filter(i<15);

Stream< Integer > strm2 = strm1.parallel().filter(i->i>5).filter(i->i<15).sequential();

Stream< Integer > strm2 = strm1.collect(
Collectors.partitioningBy(i->{ return i>5 && i<15; })
).get("true").stream();

Stream< Integer > strm2 = strm1.map(i-> i>5?i<15?i:null:null);

None

Q40. Given the following code:

import java.util.Arrays;
import java.util.List;
public class TestClass {
public static void main(String[] args) {
List al = Arrays.asList(100, 200, 230, 291, 43);

System.out.println( *INSERT CODE HERE* );
}
}

Which of the following options will correctly print the number of elements that are less than 200?

Select 1 option(s):

al.asStream().reduce((i)->i<200).count();

al.stream().map((i)->i<200, i).count();

al.stream().filter((i)->i<200).list().count();

al.stream().filter((i)->i<200).count();

al.asStream().filter((i)->i<200).count();

None

Q41. What will be the output?

var ca = new char[]{'a', 'b', 'c', 'd'};
var i = 0;
for(var c : ca){
switch(c){
case 'a' : i++;
case 'b' : ++i;
case 'c'|'d' : i++;
}
}
System.out.println("i = "+i);

Select 1 option(s):

Compilation failure

i = 5

i = 6

i = 7

None

Q42. What will the following class print when run?

public class Sample{
public static void main(String[] args) {
String s1 = """
java \
java\
""";
StringBuilder s2 = new StringBuilder("news");
s1.replace("java", "");
s2.append(s1);
System.out.println(s2.indexOf("java"));
}
}

Select 1 option(s):

0

-1

4

5

None

Q43. How will you initialize a DateTimeFormatter object so that the following code will print the number of the month (i.e. 02 for Feb, 12 for Dec, and so on) and a two digit calendar year of any given date?

System.out.println(dtf.format(LocalDate.now()));

Select 1 option(s):

DateTimeFormatter sdf = DateTimeFormatter.ofPattern("mm/yy");

DateTimeFormatter sdf = DateTimeFormatter.ofPattern("MM/yy");

DateTimeFormatter sdf = DateTimeFormatter.ofPattern("mm/YY");

DateTimeFormatter sdf = DateTimeFormatter.ofPattern("MM/YY");

None

Q44. Which of the following can be valid declarations of an integer variable?

Select 2 option(s):

Q45. Which of the following statements are true?

Select 2 option(s):

System.out.println(1 + 2 + "3"); will print 33.

System.out.println("1" + 2 + 3); will print 15.

System.out.println(4 + 1.0f); will print 5.0

System.out.println(5/4); will print 1.25

System.out.println('a' + 1 ); will print b.

Q46. Which of the following implementations of a max() method will correctly return the largest value?

Select 1 option(s):

int max(int x, int y){
return( if(x > y){ x; } else{ y; } );
}

int max(int x, int y){
return( if(x > y){ return x; } else{ return y; } );
}

int max(int x, int y){
switch(x < y){
case true:
return y;
default :
return x;
};
}

int max(int x, int y){
var m = x > y?x :y;
return m;
}

int max(var x, var y){
if(x > y) return x;
return y;
}

int max(int x, int y){
return switch(x < y){
case true -> y;
default -> x;
};
}

None

Q47. Which of the following statements correctly obtains a reference to a Console object?

Select 1 option(s):

Console c = Console.getInstance();

Console c = new Console();

Console c = new Console(System.in);

Console c = new Console(new InputStreamReader(System.in));

Console c = System.console();

None

Q48. Given:

public class SimpleLoop {
public static void main(String[] args) {
int i=0, j=10;
while (i<=j) {
i++;
j--;
}
System.out.println(i+" "+j);
}
}

What is the result?

Select 1 option(s):

6 4

6 5

6 6

5 3

5 4

5 5

None

Q49. Given:

sealed interface Member permits Student, Person{ //LINE A
String role();
}

record Person(String role) implements Member{ //LINE B
}

record Student(int id, Person person) //LINE C
implements Member //LINE D
{
public String role(){ return person.role(); } //LINE E
}

Which lines will cause compilation issues?

Select 1 option(s):

LINE A

LINE B

LINE C

LINE D

LINE E

There is no problem with any of the marked lines but the given code will not compile.

The given code will compile without any problem.

None

Q50. Given:

class T extends Thread
{
static Lock lock = new ReentrantLock();

public T(String name){ super(name); }

public void run()
{
for(int i=0; i<2; i++){
if(lock.tryLock()){
System.out.println(getName()+" got lock. "+getState());
}else{
System.out.println(getName()+" could not get lock. "+getState());
}
}
}
}
public class TestClass
{
public static void main(String args[]) throws Exception
{
T t1 = new T("T1");
t1.start();
T t2 = new T("T2");
t2.start();
Thread.sleep(1000);
}
}

What is a possible output?

Select 1 option(s):

T2 could not get lock. RUNNABLE
T1 got lock. RUNNABLE
T2 could not get lock. RUNNABLE
T1 got lock. RUNNABLE

T2 could not get lock. WAITING
T1 got lock. RUNNABLE
T2 could not get lock. WAITING
T1 got lock. RUNNABLE

T2 could not get lock. WAITING
T1 got lock. RUNNABLE
T2 could not get lock. WAITING
T1 could not get lock. WAITING

T2 could not get lock. RUNNABLE
T1 got lock. RUNNABLE
T2 could not get lock. RUNNABLE
T1 could not get lock. RUNNABLE

None

Q51. What will the following code print?

LongStream ls = LongStream.generate(()->ThreadLocalRandom.current().nextLong()%100);
Long first = ls.sorted().filter(x -> x>-10 && x<10).peek(System.out::println).findFirst().getAsLong();
System.out.println(first);

Select 1 option(s):

-10

It may print any number between -10 and 10 (excluding both).

It will print all the numbers between -10 and 10 (excluding both) followed by -9.

-9
-9

It will throw an exception at run time.

None

Q52.Consider the following code :

String id = c.readLine("%s", "Enter UserId:"); //1
System.out.println("userid is " + id); //2
String pwd = c.readPassword("%s", "Enter Password :"); //3
System.out.println("password is " + pwd); //4

Assuming that c is a valid reference to java.io.Console and that a user types jack as userid and jj123 as password, what will be the output on the console?

Select 1 option(s):

Enter UserId:jack
userid is jack
Enter Password :
password is jj123

Enter UserId:jack
userid is jack
Enter Password :*****
password is jj123

Enter UserId:jack
userid is jack
Enter Password :
password is ****

Enter UserId:jack
userid is jack
Enter Password : password is jj123

It will not compile.

None

Q53. After which line will the object created at line XXX be eligible for garbage collection?

public Object getObject(Object a) //0
{

Object b = new Object(); //XXX

Object c, d = new Object(); //1
c = b; //2
b = a = null; //3
return c; //4
}

Select 1 option(s):

//2

//3

//4

Never in this method.

Cannot be determined.

None

Q54. Given:

record Point(int x, int y){};
record Line(Point p1, Point p2){}

Which of the following are valid method implementations?

Select 3 option(s):

public double getSlope1(Line line){
if(line instanceof Line(Point(int x1, int y1), Point(int x2, int y2))){
return (y2-y1)*1.0/(x2-x1);
}else return 0.0;
}

public double getSlope2(Line line){
return switch(line){
case Line(Point(int x1, int y1), Point(int x2, int y2)) -> (y2-y1)/(x2-x1);
case null, default -> 0.0;
};
}

public double getSlope3(Line line){
return switch(line){
case line instanceof Line(Point(int x1, int y1), Point(int x2, int y2)) -> (y2-y1)*1.0/(x2-x1);
case null, default -> 0.0;
};
}

public double getSlope4(Line line){
return switch(line){
case line instanceof Line(Point(int x1, int y1), Point(int x2, int y2)) -> (y2-y1)*1.0/(x2-x1);
default -> 0.0;
};
}

public double getSlope5(Line line){
return switch(line){
case Line(Point(int x1, int y1), Point(int x2, int y2)) -> (y2-y1)/(x2-x1);
case null -> 0.0;
};
}

Time's up