Java Standard Test 11 – For Java SE 21 exam 1Z0-830 

Take Practice Test 11 from the Free Java SE 21 Developer Professional certification exam 1Z0-830 practice tests if you are tired of rereading the same chapter. Practice forces a choice. Review then shows the rule you missed. Repeat that cycle until the score is stable, not lucky. Candidates who do this walk into the official exam with a plan instead of adrenaline.

Java SE 21 certification benefits help career switchers and new graduates look credible next to people who already have a job title. Recruiters still need a reason to call. A current certification can be that reason, especially while you build projects. Java remains one of the most popular languages used by enterprise companies, and job offers in Java show up in product engineering as well as corporate IT. Netflix, Salesforce, and Adobe hire Java developers for services that customers use every day.

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 on the contact us page and read SynergisticIT JOPP.

Welcome to your Standard Test 11 - 2025

Name

Email

Phone

Q1. Given the following resource bundle files:

In file msgs.properties:
accountinfo={0} = {1}

In file msgs_en.properties:
accountinfo={0}''s balance is {1}
(Note that an extra ' is used to escape '.)

In file msgs_en_GB.properties:
accountinfo=Hi {0}, your balance is {1}

In file msgs_fr.properties:
accoutinfo=Salut {0}, ton solde est de {1}
(Note that the key name has a typing mistake in this file.)

What will the following code print?
public class TestClass {
public static void showBalance(String ownerName){
Locale.setDefault(Locale.of("en", "GB"));
ResourceBundle rb = ResourceBundle.getBundle("msgs", Locale.of("fr"));
NumberFormat nf = NumberFormat.getCurrencyInstance();
String message = rb.getString("accountinfo");
message = MessageFormat.format(message, ownerName, nf.format(100));
System.out.println(message);
}
public static void main(String[] args) {
showBalance("Bob");
}
}

Select 1 option(s):

Hi Bob, your balance is £100.00

Hi Bob, your balance is 100.00 €

Bob = 100.00 €

Bob = £100.00

Bob's balance is £100.00

None

Q2. 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?

Select 2 option(s):

var pw = new PrintWriter(os);
pw.write(1);
Size of the file depends on default character encoding.

os.write(99);
A file of size 1 byte will be created.

var bos = new BufferedOutputStream(os);
var pw = new PrintWriter(bos);
pw.print(99);
A file of size 1 byte will be created.

os.writeInt(99);
A file of size 4 bytes will be created.

var pw = new PrintWriter(os);
pw.writeInt(1);
A file of size 4 bytes will be created.

Q3. Given the following code:

List aList = List.of(40, 30, 20); //1
List bList = List.copyOf(aList); //2

bList.sort((Integer::compare)); //3
System.out.println( bList ); //4

aList.sort((Integer::compare)); //5
System.out.println( aList ); //6

Identify correct statement.

Select 1 option(s):

Line //2 will cause compilation failure.

Lines //3 and //5 will cause compilation failure.

Lines //3 and //5 will cause an java.lang.UnsupportedOperationException to be thrown at runtime.

Only line //3 will cause an java.lang.UnsupportedOperationException to be thrown at runtime.

Only line //5 will cause an java.lang.UnsupportedOperationException to be thrown at runtime.

There will be no compilation error or exception at runtime, but both the print statements will print unsorted values.

Line //3 will cause an java.lang.UnsupportedOperationException to be thrown at runtime.
Line //5 will not cause any exception at runtime.
Line //6 will print sorted values.

None

Q4. What will the following program print?

class LoopTest{
public static void main(String args[]) {
var counter = 0;
outer:
for (var i = 0; i < 3; i++) {
middle:
for (var j = 0; j < 3; j++) {
inner:
for (var k = 0; k < 3; k++) {
if (k - j > 0) {
break middle;
}
counter++;
}
}
}
System.out.println(counter);
}
}

Select 1 option(s):

2

3

6

7

9

None

Q5. What will be the output when the following code is compiled and run?

//in file Test.java
class E1 extends Exception{ }
class E2 extends E1 { }
class Test{
public static void main(String[] args){
try{
throw new E2();
}
catch(E1 e){
System.out.println("E1");
}
catch(Exception e){
System.out.println("E");
}
finally{
System.out.println("Finally");
}
}
}

Select 1 option(s):

It will not compile.

It will print E1 and Finally.

It will print E1, E and Finally.

It will print E and Finally.

It will print Finally.

None

Q6. Given the following code:

var raf = new RandomAccessFile("c:\\temp\\test.txt", "rwd");
raf.writeChars("hello");
raf.close();

Which of the following statements are correct?

(Assume that the code has appropriate security permissions.)

Select 1 option(s):

If the file test.txt does not exist, an attempt will be made to create it.

If the file test.txt does not exist, an exception will be thrown.

If the file test.txt exists, an exception will be thrown.

If the file test.txt exists, it will be overwritten and all the existing data will be lost.

If the file test.txt exists, the given characters will be appended to the end of the existing data.

None

Q7. What will the following code print when compiled and run?

var nameList = new ArrayList();
nameList.add("Ally");
nameList.add("Billy");
nameList.add("Cally");
nameList.add("Billy");
nameList.add("Ally");

var nameSet1 = new HashSet();
for(var name:nameList) nameSet1.add(name);
var nameSet2 = new HashSet(nameList);
System.out.println(nameList.size()+" "+nameSet1.size()+" "+nameSet2.size());

Select 1 option(s):

5 3 5

5 3 3

5 3 1

3 3 1

5 5 5

5 5 1

None

Q8. Given:

public record Book(String title, Double price){ };

What will the following code print?

List books = Arrays.asList(
new Book("Gone with the wind", 5.0),
new Book("Gone with the wind", 10.0),
new Book("Atlas Shrugged", 15.0)
);
books.stream().collect(Collectors.toMap((b->b.title()), b->b.price()))
.forEach((a, b)->System.out.println(a+" "+b));

Select 1 option(s):

Gone with the wind 5.0
Atlas Shrugged 15.0

Gone with the wind 10.0
Atlas Shrugged 15.0

Gone with the wind 5.0
Gone with the wind 10.0
Atlas Shrugged 15.0

It will throw an exception at run time.

None

Q9. What will the following code print when compiled and run:

public class TestClass {

public static void main(String[] args){
var k = 2;
while(--k){
System.out.println(k);
}
}
}

Select 1 option(s):

1

1
0

2
1

2
1
0

It will keep printing numbers in an infinite loop.

It will not compile.

None

Q10. Identify correct statements about java.io.Console class?

Select 1 option(s):

You can read character data from a console but not write to it.

You can read both binary and character data from Console object but you cannot write to it.

You can read both binary and character data from Console object but you can only write character data to it.

You can read as well as write only character data from/to it.

None

Q11. Identify correct statements about Java exceptions.

Select 1 option(s):

Errors and its subclasses are meant for situations from which an application can recover while RuntimeException and its subclasses are meant for situations from which an application cannot recover.

RuntimeException and its subclasses are used for recoverable situations.

Neither Errors nor RuntimeExceptions are used for recoverable situations. RuntimeExceptions should be identified during testing and eliminated by fixing the code, while Errors should be eliminated by fixing the environment.

Both Errors and RuntimeExceptions are recoverable and should be caught. A helpful message should be shown to the user instead of generating a stack trace on the console.

None

Q12. You are writing a piece of code that determines taxRate on a given grossIncome. The taxRate is to be computed as follows -

If grossIncome is less than or equals to 18000, taxRate is 0.
If grossIncome is more than 18000 but less than or equal to 36000, taxRate is 10%
If grossIncome is more than 36000, taxRate is 20%.

Which of following code fragments do it correctly?

Select 3 option(s):

double taxRate = grossIncome<=18000 ? 0 : (grossIncome<=36000) ? .1 : .2;

double taxRate = .2;
taxRate = grossIncome<=18000?0:.1;
taxRate = grossIncome<=36000?.1:.2;

double taxRate = 0;
if(grossIncome>36000) taxRate = .20;
if(grossIncome>18000 && grossIncome<=36000) taxRate = .10;

double taxRate = .2;
if(grossIncome>36000) {
taxRate = .2;
}else taxRate = 0;
if(grossIncome>18000 ) {
taxRate = .1;
}

double taxRate = 0;
taxRate = grossIncome>18000?grossIncome<=36000?.1:.2:0;

Q13. What will the following code print?

Duration d = Duration.ofDays(1);
System.out.println(d);
d = Duration.ofMinutes(0);
System.out.println(d);
Period p = Period.ofMonths(0);
System.out.println(p);

Select 1 option(s):

PT1D
PT0M
P0M

PT24H
PT0S
P0D

PT0S
PT0M
P0M

0
PT0S
P0D

None

Q14. What will the following code print when compiled and run?

var tickers = List.of("A", "D", "E", "C", "A");
var ratio = List.of(1.0, 1.2, 1.5, 1.8, 2.0);
var map1 = IntStream.range(0, tickers.size())
.boxed()
.collect(Collectors.toMap(
i -> tickers.get(i),
i -> 1.0/ratio.get(i), (x, y) -> x+y)) ; //<<----- LINE 1

var map2 = map1.entrySet().stream().sorted(Map.Entry.comparingByKey())
.collect(
Collectors.toMap(
Map.Entry::getKey,
Map.Entry::getValue,
(x, y) -> x-y,
LinkedHashMap::new)
); //<<----- LINE 2

map2.forEach((var k, var v)->System.out.printf("%s = %.2f\n",k, v));

Select 1 option(s):

A = 1.50
C = 0.56
D = 0.83
E = 0.67

E = 0.67
D = 0.83
C = 0.56
A = 1.50

exception at line 1.

exception at line 2.

A = 1.50
D = 0.83
E = 0.67
C = 0.56
A = 1.50

None

Q15. What will the following program print when run?

public class ChangeTest {

private int myValue = 0;

public void showOne(int myValue){
myValue = myValue;
System.out.println(this.myValue);
}

public void showTwo(int myValue){
this.myValue = myValue;
System.out.println(this.myValue);
}
public static void main(String[] args) {
var ct = new ChangeTest();
ct.showOne(100);
ct.showTwo(200);
}
}

Select 1 option(s):

0 followed by 100.

100 followed by 100.

0 followed by 200.

100 followed by 200.

None

Q16. What will the following code snippet print?

List s1 = new ArrayList( );
try{
while(true){
s1.add("sdfa");
}
}catch(RuntimeException e){
e.printStackTrace();
}
System.out.println(s1.size());

Select 1 option(s):

It will not compile.

It will print a RuntimeException stack trace from the catch clause.

It will throw an error at runtime that will not be caught by the catch block.

It will print a stack trace from the catch clause and a number depending on the memory available in the system.

It will only print a number depending on the memory available in the system.

None

Q17. Which is the earliest line in the following code after which the object created on line // 1 can be garbage collected, assuming no compiler optimizations are done?

public class NewClass{
private Object o;
void doSomething(Object s){ o = s; }

public static void main(String args[]){
Object obj = new Object(); // 1
NewClass tc = new NewClass(); //2
tc.doSomething(obj); //3
obj = new Object(); //4
obj = null; //5
tc.doSomething(obj); //6
}
}

Select 1 option(s):

Line 1

Line 2

Line 3

Line 4

Line 5

Line 6

None

Q18. Which statements about the following code are correct?

interface House{
public default String getAddress(){
return "101 Main Str";
}
}

interface Office {
public default String getAddress(){
return "101 Smart Str";
}
}

class HomeOffice implements House, Office{
public String getAddress(){
return "R No 1, Home";
}
}

public class TestClass {

public static void main(String[] args) {
House h = new HomeOffice(); //1
System.out.println(h.getAddress()); //2
}
}

Select 1 option(s):

Code for class HomeOffice will cause compilation to fail.

Line at //1 will cause compilation to fail.

Line at //2 will cause compilation to fail.

The code will compile successfully if the getAddress method is removed from class HomeOffice.

It will compile fine and print R No 1, Home when run.

None

Q19. Identify correct statements about the following code:

import java.util.*;

class Student{
int marks;
}

class TestClass {
var k = new Student(); //1

public static void main(String[] args) {

var s = new Student(){ //2
@Override
public String toString(){ return "student obj"; };
};

var slist = Set.of(new Student()); //3

for(var i : slist){ //4
System.out.println(i);
}

slist.removeIf((var s1) -> s1.marks<0); //5
}
}

Select 1 option(s):

It will compile without any error.

Compilation error at //1

Compilation error at //2

Compilation error at //3

Compilation error at //4

Compilation error at //5

None

Q20. Given:

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

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

static StringBuilder data = new StringBuilder();

public void run()
{
if(lock.tryLock()){
try{
lock.lock();
data.append("hello");
}finally{
lock.unlock();
}
}
}
}
public class TestClass
{
public static void main(String args[]) throws Exception
{
T t1 = new T("T1");
t1.start();
try{
t1.lock.lock();
System.out.println(t1.data);
}finally{
t1.lock.unlock();
}

}
}

Identify correct statement(s) about the above code.

Select 2 option(s):

It may print hello and end.

It may print hello but the program will not end (i.e. it will hang).

It will never print hello.

The program will either hang or it will terminate after printing an empty string.

It may print an empty string and then hang.

Q21. Given:

module abc.print{
requires org.pdf;
provides org.pdf.Print with com.abc.print.PrintImpl;
}

Identify correct statements about the above module.

Select 1 option(s):

org.pdf.Print must be an interface.

org.pdf.Print must be an interface or an abstract class.

com.abc.print.PrintImpl must have a no-args constructor.

com.abc.print.PrintImpl must implement (or extend) org.pdf.Print.

None of the above are correct.

None

Q22. Given:

public static float parseFloat1(String s1){
try{
return Float.parseFloat(s1);
}catch(NumberFormatException e){
return 0.0f;
}catch(IllegalArgumentException e){
return Float.NaN;
}
}

Identify correct statements.

Select 1 option(s):

Calling parseFloat1(""+Float.NEGATIVE_INFINITY); will return 0.0f.

Calling parseFloat1(""+Float.POSITIVE_INFINITY); will return 0.0f.

Calling parseFloat1("junk"); will return 0.0f.

Calling parseFloat1("-Infinity"); will return NaN.

Calling parseFloat1("NaN"); will return 0.0f.

None

Q23. Given:

enum Card
{
HEART, CLUB, SPADE, DIAMOND;
}

Which of the following code fragments will print
HEART CLUB SPADE DIAMOND
in that order?

Select 1 option(s):

for(var i=0; i<4; i++) System.out.println(Card[i]+" ");

while(Card.hasNext()) System.out.println(Card.next()+" ");

for(var c : Card.values()) System.out.print(c+" ");

for(var i=0; i<4; i++) System.out.println(Card.ordinal(i)+" ");

None of these.

None

Q24. What will be the result of attempting to compile and run the following program?

public class TestClass{
public static void main(String args[]){
try{
RuntimeException re = null;
throw re;
}
catch(Exception e){
System.out.println(e);
}
}
}

Select 1 option(s):

The code will fail to compile, since RuntimeException cannot be caught by catching an Exception.

The program will fail to compile, since re is null.

The program will compile without error and will print java.lang.RuntimeException when run.

The program will compile without error and will print java.lang.NullPointerException when run.

The program will compile without error and will run and print null.

None

Q25. What will the following code print?

var ca = new char[]{'a', 'b', 'c', 'd', 'e'};
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):

i = 3

i = 4

i = 5

i = 6

Compilation failure because default statement is necessary in this situation.

None

Q26. What will the following code print when compiled and run?

class StringWrapper {
private String theVal;
public StringWrapper(String str){ this.theVal = str; }
}
public class Tester{
public static void main(String[] args) {
StringWrapper sw = new StringWrapper("How are you?");
StringBuilder sb = new StringBuilder("How are you?");
System.out.println("Hello, "+sw);
System.out.println("Hello, "+sb);
}
}

Select 1 option(s):

Hello, How are you?
Hello, How are you?

Hello, StringWrapper@< hashcode >
Hello, How are you?

Hello, How are you?
Hello, StringBuilder@< hashcode >

Hello, How are you?
Hello, java.lang.StringBuilder@< hashcode >

Hello, StringWrapper@< hashcode >
Hello, java.lang.StringBuilder@< hashcode >

None

Q27. Which of the following statements are acceptable?

Select 4 option(s):

Object o = new java.io.File("a.txt");
(Assume that java.io.File is a valid class with a constructor that takes a String.)

Boolean bool = false;

char ch = 10;

Thread t = new Runnable();
(Assume that Runnable is a valid interface.)

Runnable r = new Thread();
(Assume that Thread is a class that implements Runnable interface)

Q28. Given:

List letters = Arrays.asList("j", "a", "v","a");
String word = INSERT CODE HERE
System.out.println(word);

Which of the following code fragments when inserted in the above code independent of each other will cause it to print java?

Select 1 option(s):

None

Q29. What will be a part of the output when the following code is compiled and run?

class Boo {
int boo = 10;
public Boo(int k){ System.out.println("In Boo k = "+k); boo = k;}
}

class BooBoo extends Boo {
public BooBoo(int k ){ super(k); System.out.println("In BooBoo k = "+k); }
}

class Moo extends BooBoo implements Serializable {
int moo = 10;
public Moo(){ super(5); System.out.println("In Moo"); }
}

public class TestClass {

public static void main(String[] args) throws Exception{

var moo = new Moo();
var fos = new FileOutputStream("c:\\temp\\moo1.ser");
var os = new ObjectOutputStream(fos);
os.writeObject(moo);
os.close();
var fis = new FileInputStream("c:\\temp\\moo1.ser");
var is = new ObjectInputStream(fis);
moo = (Moo) is.readObject();
is.close();
}
}

Select 3 option(s):

In Boo k = 5
In BooBoo k = 5

In Boo k = 0
In BooBoo k = 0

In Moo

It will throw an exception at runtime.

It will not compile.

Q30. Given:

record Person(String name, char gender){};

What will be the output of the following code:

Stream.of(new Person("Bob", 'M'), new Person("Rita", 'F'),
new Person("Mukesh", 'M'), new Person("Amita", 'T'),
new Person("Sonya", 'F'))
.takeWhile(p->p.gender()=='M' || p.gender()=='F')
.sorted( (p1, p2) -> p2.name().compareTo(p1.name()))
.dropWhile(p->p.name().length()<5)
.forEach(p->System.out.print(p.name()));

Select 1 option(s):

BobMukesh

SonyaRitaMukeshBobAmit

MukeshBob

BobRita

RitaBob

It will run fine but will not print any name.

None

Q31. What will the following code print when compiled and run?

List messages =
Arrays.asList(new StringBuilder(), new StringBuilder());
messages.stream().forEach(s->s.append("helloworld"));
messages.forEach(s->{
s.insert(5,",");
System.out.println(s);
});

Select 1 option(s):

It will not print anything.

It will not compile.

It will throw IllegalStateException at runtime.

hello,world
hello,world

helloworld
helloworld

None

Q32. Consider :

class A { public void perform_work(){} }
class B extends A { public void perform_work(){} }
class C extends B { public void perform_work(){} }

How can you let perform_work() method of A to be called from an instance method in C?

Select 1 option(s):

( (A) this ).perform_work( );

super.perform_work( );

super.super.perform_work( );

this.super.perform_work( );

It is not possible.

None

Q33. What will the following code print when compiled and run?

Select 1 option(s):

Hello : BillGeorgeObama

Hello : BillHello : GeorgeHello : Obama

BillGeorgeObamaHello :

BillGeorgeObama

It will throw an exception at run time.

None

Q34. Complete the following code:

enum Card {
CLUB, DIAMOND, HEART, SPADE
}

public class TestClass{

public static String getColor(Card c){

INSERT CODE HERE

}
public static void main(String[] args) {
System.out.println(getColor(Card.CLUB));
}
}

Select 2 option(s):

return switch(c){
case CLUB, SPADE -> "BLACK"; break;
case DIAMOND, HEART -> "RED";
};

return switch(c){
case CLUB, SPADE -> "BLACK";
case DIAMOND, HEART -> "RED";
default -> "YELLOW";
};

switch(c){
case CLUB, SPADE -> return "BLACK";
case DIAMOND, HEART -> return "RED";
};

return switch(c){
case CLUB, SPADE -> "BLACK";
};

return switch(c){
case CLUB, SPADE -> { yield "BLACK"; }
case DIAMOND, HEART -> { yield "RED"; }
};

Q35. What will be the output of the following program?

class TestClass{
public static void main(String[] args) throws Exception{
try{
amethod();
System.out.println("try ");
}
catch(Exception e){
System.out.print("catch ");
}
finally {
System.out.print("finally ");
}
System.out.print("out ");
}
public static void amethod(){ }
}

Select 1 option(s):

try finally

try finally out

try out

catch finally out

It will not compile because amethod() does not throw any exception.

None

Q36. What will the following code print?

DateTimeFormatter df = DateTimeFormatter.ofPattern("eeee");
LocalDate d = LocalDate.of(2000, 1, 1); //assume that it was Saturday on this date
System.out.println(df.format(d));

Select 1 option(s):

Satu

Saturday

Sat

0007

7

None

Q37. What will the following code print when compiled and run?

public class Device implements AutoCloseable{
boolean open = false;
int index;
public Device(int index){
this.index = index;
open = true;
}

public void write() throws IOException{
throw new RuntimeException("Can't write!");
}

public void close(){
open = false;
System.out.println("Device closed "+index);
}

public static void main(String[] args) {
Device d1 = new Device(1);
try(d1;
Device d2 = new Device(2);
Device d3 = new Device(3)){
d2.write();
d1.close();
}catch(Exception e){
System.out.println("Got Exception "+e.getMessage());
}
}
}

Select 1 option(s):

Device closed 3
Device closed 2
Got Exception Can't write!

Device closed 2
Device closed 3
Got Exception Can't write!

Device closed 1
Device closed 2
Device closed 3
Got Exception Can't write!

Device closed 1
Device closed 3
Device closed 2
Got Exception Can't write!

Device closed 3
Device closed 2
Device closed 1
Got Exception Can't write!

None

Q38. What will be the result of compiling and running the following code?

class Base{
public Object getValue(){ return new Object(); } //1
}

class Base2 extends Base{
public String getValue(){ return "hello"; } //2
}

public class TestClass{
public static void main(String[] args){
Base b = new Base2();
System.out.println(b.getValue()); //3
}
}

Select 1 option(s):

It will print the hash code of the object.

It will print hello.

Compile time error at //1.

Compile time error at //2.

Compile time error at //3.

None

Q39. Consider the following code:

public class TestOuter
{
public void myOuterMethod()
{
// 1
}
public class TestInner { }
public static void main(String[] args)
{
var to = new TestOuter();
// 2
}
}

Which of the following options correctly instantiates a TestInner object?

Select 2 option(s):

new TestInner(); at //1

new TestInner(); at //2

new to.TestInner(); at //2

new TestOuter.TestInner(); at //2

new TestOuter().new TestInner(); at //1

Q40. Which digits and in what order will be printed when the following program is run?

public class TestClass{
public static void main(String args[]){
int k = 0;
try{
int i = 5/k;
}
catch (ArithmeticException e){
System.out.println("1");
}
catch (RuntimeException e){
System.out.println("2");
return ;
}
catch (Exception e){
System.out.println("3");
}
finally{
System.out.println("4");
}
System.out.println("5");
}
}

Select 1 option(s):

The program will print 5.

The program will print 1 and 4, in that order.

The program will print 1, 2 and 4, in that order.

The program will print 1, 4 and 5, in that order.

The program will print 1,2, 4 and 5, in that order.

None

Q41. Which of the following statements about deadlock is correct?

Select 1 option(s):

A deadlock occurs when threads become so busy in responding to each other that they are unable to perform any real work.

Deadlock occurs when a thread is frequently unable to get access to a resource because the resource is hogged by other threads most of the time.

Thread 1 and 2 are said to be deadlocked when Thread 1 is blocked waiting for Thread 2 to release a resource, while Thread 2 is blocked waiting for Thread 1 to release another resource.

A deadlock is caused by starvation, which in turn is caused by a live lock.

A deadlock is caused when, in a multi core CPU system, one of the cores get offline or corrupt.

Using virtual threads prevents deadlocks.

None

Q42. What will the following code print when run?

class MyCallable implements Callable{
public String call() throws Exception {
Thread.sleep(50000);
return "DONE";
}
}
public class TestClass {

public static void main(String[] args) throws Exception {
var es = Executors.newSingleThreadExecutor();
var future = es.submit(new MyCallable());
System.out.println(future.get()); //1
es.shutdownNow(); //2
}
}

Select 1 option(s):

DONE

null

It will throw an exception at run time at line marked //1

It will throw an exception at run time at line marked //2

None

Q43. Which of the following declarations is/are valid inside a static method:

1. bool b = null;

2. boolean b = 1;

3. boolean b = true|false;

4. bool b = (10<11);

5. boolean b = true||false;

6. var b = 10>11;

Select 1 option(s):

1 and 4

2, 3, 5, and 6

2 and 3

3, 5, and 6

5 and 6

3 and 5

1, 4, and 6

None

Q44. Given:

public class TestClass
{
public static void main(String args[])
{
B b = new C();
A a = b;

INSERT CODE HERE

}
}
class A {
void a(){ System.out.println("a"); }
}
class B extends A {
void b(){ System.out.println("b"); }
}
class C extends B {
void c(){ System.out.println("c"); }
}

What can be inserted in the above code?

Select 3 option(s):

if (a instanceof A a1) a1.a();

if (a instanceof B b1) b1.a();

if (a instanceof B b2) b2.c();

if (a instanceof C c1) c1.c();

Q45. What will the following class print when executed?

class Test{
static boolean a;
static boolean b;
static boolean c;
public static void main (String[] args){
boolean bool = (a = true) || (b = true) && (c = true);
System.out.print(a + ", " + b + ", " + c);
}
}

Select 1 option(s):

true, false, true

true, true, false

true, false, false

true, true, true

None

Q46. Given:

abstract class Base{
abstract int power();
}

class A extends Base{
@Override
int power(){ return 0; }
}

class AA extends A{
@Override
int power(){ return 1; }
void mAA(){
System.out.println("mAA");
}
}

class B extends Base{
@Override
int power(){ return 1; }
}

public class TestClass
{

void processBase(Base base){
INSERT CODE HERE
}

}

What can be inserted in the above code?

Select 2 option(s):

if(base instanceof A a && a instanceof AA aa ){
aa.mAA();
}

if(base instanceof A a && a.power() == 1 ){
a.mAA();
}

if(base instanceof A a && a.power() == 1 ){
((AA)a).mAA();
}

if(base instanceof B b || base instanceof A a ){
if(b!=null) System.out.println(b.power());
if(a!=null) System.out.println(a.power());
}

Q47. Given:

public class TestClass
{
static class Calculation implements Runnable
{
int result;
public void run()
{
synchronized(this){
try{
Thread.sleep(5000); //LINE 10
result = 101;
}catch(Exception e){ e.printStackTrace(); }
}
}
}
public static void main(String args[]) throws Exception
{
Calculation c = new Calculation();
Thread.Builder tb = Thread.ofPlatform();
Thread t = tb.unstarted(c);
t.start();
Thread.sleep(100);
synchronized(c){ //LINE 21
System.out.println("Result is "+c.result);
}
}

}

Assuming that the calculation thread has just executed the line marked //LINE 10 and the main thread has just executed the line marked //LINE 21, what are the states of the two threads?

Select 1 option(s):

main thread: WAITING
calculation thread: WAITING

main thread: WAITING
calculation thread: TIMED_WAITING

main thread: BLOCKED
calculation thread: TIMED_WAITING

main thread: BLOCKED
calculation thread: WAITING

main thread: BLOCKED
calculation thread: BLOCKED

None

Q48. Given:

public class Book{
private String title;
private Double price;
public Book(String title, Double price){
this.title = title;
this.price = price;
}
//accessor methods not shown
}

What will the following code print when compiled and run?

Book b1 = new Book("Java in 24 hrs", 30.0);
Book b2 = new Book("Thinking in Java", null);
Supplier s1 = b1::getPrice;
System.out.println(b1.getTitle()+" "+s1.get());
Supplier s2 = b2::getPrice;
System.out.println(b2.getTitle()+" "+s2.getAsDouble());

Select 1 option(s):

Java in 24 hrs 30.0
< exception stack trace >

Java in 24 hrs 30.0
Thinking in Java 0.0

< exception stack trace >

It will not compile.

None

Q49. Consider that str is a local variable of class java.lang.String.

Which of the following lines of code may throw a NullPointerException in certain situations?

Or a tougher version of the question could be :
Which of the following lines of code are not an example of robust design ?

Select 3 option(s):

if ( (str != null) | ( i == str.length() ) )

if ( (str == null) | ( i == str.length() ) )

if ( (str != null) || (i == str.length() ) )

if ( (str == null) || (i == str.length() ) )

Q50. You are creating an acme.accounting module that depends on acme.math module and makes its com.acme.accounting package available to all other modules. Which of the following files correctly defines this module?

Select 1 option(s):

//In file module.java:
module acme.accounting{
requires acme.math;
exports com.acme.accounting;
}

//In file module.java:
module acme.accounting{
requires acme.math.*;
exports com.acme.accounting.*;
}

//In file module.java:
module acme.accounting{
requires acme.math;
exports com.acme.accounting.*;
}

//In file module-info.java:
module-info acme.accounting{
requires acme.math;
exports com.acme.accounting;
}

//In file module-info.java:
module acme.accounting{
requires acme.math;
exports com.acme.accounting.*;
}

//In file module-info.java:
module acme.accounting{
requires acme.math;
exports com.acme.accounting;
}

None

Time's up