Java Foundation Test 3 – exam 1Z0-830 practice test

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Welcome to your Foundation Test 3 – 2025

Name

Phone

Q1. Which of these statements concerning nested classes and interfaces are true?

Select 3 option(s):

An instance of a static nested class has an inherent outer instance.

A static nested class can contain non-static member variables.

A static nested interface can contain static member variables.

A static nested interface has an inherent outer instance associated with it.

For each instance of the outer class, there can exist many instances of a non-static inner class.

An inner class cannot have static members.

Q2. Identify correct statement(s) about Java records.

Select 2 option(s):

Records are implicitly final.

Records are implicitly static.

Records are meant to restrict the number of instances of that type.

Records are implicitly sealed.

Record instances are immutable.

Q3. You want to find out whether two strings are equal or not, in terms of the actual characters within the strings. What is the best way to do this?

Select 1 option(s):

use String's equals method.

use String's equalsIgnoreCase method.

Use == operator.

Use String's match method.

Use String's intern method.

Q4. Which of the following statements about starvation is correct?

Select 1 option(s):

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

Starvation 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.

Starvation is a symptom of live lock in the threads.

Starvation is a symptom of deadlock in the threads.

Starvation is caused by combining platform threads and virtual threads.

Q5. Which of the following statements are true?

Select 3 option(s):

private keyword can never be applied to a class.

synchronized keyword can never be applied to a class.

synchronized keyword may be applied to a non-primitive variable.

final keyword can never be applied to a class.

A final variable can be hidden in a subclass.

sealed and non-sealed keywords can only be applied to classes and interfaces, not to enums and records.

Q6. Identify true statements about sealed classes.

Select 1 option(s):

A sealed class cannot be extended.

A sealed interface cannot be extended.

Only a class can be sealed and not an interface.

All reference types - classes, interfaces, enums, and records - can be marked as sealed.

None of the above.

Q7. The opening delimiter of a Java text block is:

Select 1 option(s):

"""

""" immediately followed by a new line

""" followed by any number of white spaces and then a new line

""" followed by one or more white spaces

Q8. What will the following code print?

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

Select 1 option(s):

It will not compile.

It will throw an exception at runtime.

It will print numbers from 0 to 8

It will print numbers from 0 to 3

It will print numbers from 0 to 4

Q9. Given the following code:

abstract class Device{
String name;
String number;
String address;
int frequency;

abstract void setName(String name);
abstract void connect();
abstract void disconnect();
abstract void call(String number);
abstract void listenOn(int frequency);

}

interface Caller{ }

interface Receiver{ }

class Phone extends Device implements Caller{ }
class TV extends Device implements Receiver{ }
class WalkieTalkie extends Device implements Caller, Receiver{ }

and the following requirements specification regarding the call and listenOn functionality:

1. Phone supports only the call operation. Users should have the ability to call a number, but not set the frequencey. Assume frequency is fixed at 0.

2. TV supports only the listenOn operation. Users should have the ability to set the frequency using the listenOn method, but not change the number. Assume number is fixed at "0".

3. WalkieTalkie contains both call and listenOn features. Users should have the ability to call a number using call as well as set frequency using listenOn.

The methods setName, connect, and disconnect are applicable to Phone, TV, and WalkieTalkie.

Which two changes together would allow you to achieve these specifications?

Select 2 option(s):

make Device an interface rather than an abstract class

move String number from Device to Caller

move int frequency from Device to Receiver

make Device, rather than Phone, TV, and WalkieTalkie implement Caller and Receiver.

move call from Device to Caller

move listenOn from Device to Receiver

Q10. Which is/are the root interface(s) for all collection related interfaces?

Select 2 option(s):

BaseCollection

Collection

List

Set

Map

Q11. Which of the following are NOT valid operators in Java?

Select 4 option(s):

sizeof

<<<

instanceof

mod

equals

Q12. Using a Callable would be more appropriate than using a Runnable in which of the following situations?

Select 1 option(s):

When you want to execute a task directly in a separate thread.

When your task might throw a checked exception and you want to execute it in a separate Thread.

When your task does not return any result but you want to execute the task asynchronously.

When you want to use ExecutorService to submit multiple instances of a task.

When you want to use virtual threads.

Q13. Which of the following command line switches is required (independent of each other) to run a modular application stored in c:\modules\movies.jar?

Select 3 option(s):

-m c:\modules\movies.jar

-p c:\modules\movies.jar

-p c:\modules

--path c:\modules\movies.jar

--module-path c:\modules

Q14. Given:

//In file AccessTest.java
package a;
public class AccessTest {
int a;
private int b;
protected void c(){ }
public int d(){ return 0; }
}

//In file AccessTester.java
package b;
import a.AccessTest;

public class AccessTester extends AccessTest{
public static void main(String[] args) {
AccessTest ref = new AccessTest();

}
}

Identity the correct statements -

Select 1 option(s):

Only c() and d() can be accessed by ref.

b, c(), as well as d(), can be accessed by ref.

Only d() can be accessed by ref.

Only a and d() can be accessed by ref.

Q15. Which of the following is/are valid functional interfaces?

Select 1 option(s):

interface F{
default void m(){ }
}

interface F{
default void m(){ }
static void n(){ }
}

interface F{
void m();
void n();
}

interface F{
default void m(){ }
abstract void n();
}

interface F{
void m(){ }
}

Q16. Under what situations does a class get a default constructor?

Select 1 option(s):

All classes in Java get a default constructor.

You have to define at least one constructor to get the default constructor.

If the class does not define any constructors explicitly.

All classes get default constructor from Object class.

None of the above.

Q17. Where, in a constructor, can you place a call to a super class's constructor ?

Select 1 option(s):

Anywhere in the constructor's body.

As the first statement in the constructor.

Only as the first statement and it can be called just like any other method call i.e. ClassName( ... ).

You can't call super class's constructor in a base class as constructors are not inherited.

None of the above.

Q18. Consider the following code:

Locale myLoc = new Locale("fr", "FR");
ResourceBundle rb = ResourceBundle.getBundle("appmessages", myLoc);
//INSERT CODE HERE

Which of the following lines of code will assign a ResourceBundle for a different Locale to rb than the one currently assigned?

Select 2 option(s):

rb = ResourceBundle.getBundle("appmessages", new Locale("ch", "CH"));

rb = ResourceBundle.getBundle("appmessages", CHINA);

myLoc.setLocale(Locale.CHINA);

myLoc.setLocale(new Locale("ch", "CH"));

rb = ResourceBundle.getBundle("appmessages", Locale.CHINA);

rb.setLocale(Locale.CHINA);

Q19. Which of the following are true about the enhanced for loop?

Select 3 option(s):

It can iterate over an array or a Collection but not a Map.

Using an enhanced for loop prevents the code from going into an infinite loop.

Using an enhanced for loop on an array may cause infinite loop.

An enhanced for loop can iterate over a Map.

You cannot find out the number of the current iteration while iterating.

var declaration cannot be used for declaring the loop variable.

Q20. Which of the following method(s) of java.util.stream.Stream interface is/are used for reduction?

Select 2 option(s):

filter

reduce

sum

max

add

Q21. Given the following declaration, select the correct way to get the number of elements in the array, assuming that the array has been initialized.

int[] intArr;

Select 1 option(s):

intArr[ ].length( )

intArr.length( )

intArr.length

intArr[ ].size( )

intArr.size( )

Q22. Which of the following can be used as a constructor for the class given below?

public class TestClass{
final int a;
// lots of irrelevant code
}

Select 1 option(s):

public void TestClass() { a = 10; }

public TestClass() { }

public static TestClass(int param) { a = param; }

public final TestClass() { a = 10; }

public TestClass(int x) { a = x; }

public TestClass() { System.out.println(a); }

public TestClass(int x) { System.out.println(a); a = x; }

Q23. A method with no access modifier defined in a class can be overridden by a method marked protected (assuming that it is not final) in the sub class.

Select 1 option(s):

True

False

Q24. Given that daylight Savings Time ends on Nov 6 at 2 AM in US/Eastern time zone. (As a result, 2 AM becomes 1 AM. In other words, one minute after 1.59 AM, the clock shows 1 AM instead of 2 AM.), what will the following code print?

LocalDateTime ld = LocalDateTime.of(2022, Month.NOVEMBER, 6, 1, 30);
ZonedDateTime date1 = ZonedDateTime.of(ld, ZoneId.of("US/Eastern"));
ZonedDateTime date2 = date1.plusHours(1);
System.out.println(date1.getHour()+" "+date2.getHour());

Select 1 option(s):

-1 -1

-1 -2

1 2

1 1

2 1

Q25. Which of the following tools support the --show-module-resolution option?

Select 1 option(s):

java

javac

jar

jmod

jdeps

jimage

Q26. Identify legal module names.

Select 3 option(s):

com.amazing.movie-rentals

com.amazing.movierentals

amazing-movierentals

com.amazing.$movierentals

no1movierentals

com.amazing.1movierentals

Q27. Given the following definition of class, which member variables are accessible from OUTSIDE the package com.enthu.qb?

package com.enthu.qb;
public class TestClass{
int i;
public int j;
protected int k;
private int l;
}

Select 2 option(s):

Member variable i.

Member variable j.

Member variable k.

Member variable k, but only for subclasses.

Member variable l.

Q28. Which of the following code fragments will you use to create an ExecutorService?

Select 3 option(s):

ExecutorService

Executor

Executors

.newSingleThreadExecutor();

.createSingleThreadExecutor();

.getSingleThreadExecutor();

.newVirtualThreadPerTaskExecutor();

Q29. Identify the correct statement about i18n.

Select 2 option(s):

I18N class allows you to port your code for multiple regions and/or languages.

You should use Locale and formatter objects such as NumberFormat and DateFormat to generate locale specific output.

The i18n method of NumberFormat and DateFormat allows you to generate locale specific output.

Using default locale for NumberFormat and DateFormat automatically ensures that the formatted text will be localized to the location setting of the machine on which the code is run.
(Assuming that default locale hasn't been explicitly changed by any means.)

i18n stands for Internationalization and it is handled automatically by Java.

Q30. The following code snippet will print 'true'.

short s = Short.MAX_VALUE;
char c = s;
System.out.println( c == Short.MAX_VALUE);

Select 1 option(s):

True

False

Q31. Which of the following statements are true?

Select 2 option(s):

A nested class may be declared static.

Anonymous inner class may be declared public.

Anonymous inner class may be declared private.

Anonymous inner class may be declared protected.

Anonymous inner class may extend an abstract class.

Q32. The signature of a method in a class is as follows:

public static List doIt(List nums)

This method is being called in the following code:

result = doIt(in);

Given that String implements CharSequence interface, what should be the reference type of in and result variables?

Select 1 option(s):

ArrayList< String > in;
List< CharSequence > result;

List< String > in;
List< Object > result;

ArrayList< String > in;
List result;

List< CharSequence > in;
List< CharSequence > result;

ArrayList< Object > in;
List< CharSequence > result;

None of these.

Q33. Which of these methods are defined in the Map interface?

Select 2 option(s):

contains(Object o)

addAll(Collection c)

remove(Object o)

values( )

toArray( )

Q34. Objects of which of the following classes can be thrown using a throw statement?

Select 3 option(s):

Event

Object

Throwable

Exception

RuntimeException

Q35. Consider the following method :

public void myMethod(int m, Object p, double d){
... valid code here
}

Assuming that there is no other method with the same name, which of the following options are correct regarding the above method?

Select 1 option(s):

If this method is called with two parameters, the value of d in the method will be 0.0.

If this method is called with one parameter, the value of p and d in the method will be null and 0.0 respectively.

If this method is called with one parameter, the call will throw a NullPointerException.

If this method is called with one parameter, the call will throw a NullPointerException only if the code in the method tries to access p.

If this method is called with two parameters, the code will not compile.

Q36. Identify correct statement(s) about switch expressions written using the new arrow syntax.

Select 3 option(s):

Every case block must either have a yield or a break.

Every case must either have a case expression or a case block.

Every case must return a value or throw an exception.

A switch expression must end with a semi-colon.

Q37. What is meant by "encapsulation" ?

Select 1 option(s):

There is no way to access member variable.

There are no member variables.

Member fields are declared private and public accessor/mutator methods are provided to access and change their values if needed.

Data fields are declared public and accessor methods are provided to access and change their values.

Q38. Which of the following method calls can be applied to a String object?

Select 5 option(s):

repeat(int )

equalsIgnoreCase(String)

prune()

append()

intern()

compareTo(String )

transform(Function< ? super String,? extends R > f)

Q39. Complete the following code by inserting declaration for stateCitiesMap:

//Insert line of code here

List cities = new ArrayList();
cities.add("New York");
cities.add("Albany");
stateCitiesMap.put("NY", cities);

Select 2 option(s):

Map< String, ArrayList< String > > stateCitiesMap = new HashMap< >();

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

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

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

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

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

Q40. Which of the following are correct about java.util.function.Predicate?

Select 1 option(s):

It is an interface that has only one abstract method (among other non-abstract methods) with the signature -
public void test(T t);

It is an interface that has only one abstract method (among other non-abstract methods) with the signature -
public boolean test(T t);

It is an abstract class that has only one abstract method (among other non-abstract methods) with the signature -
public abstract void test(T t);

It is an abstract class that has only one abstract method (among other non-abstract methods) with the signature -
public abstract boolean test(T t);

Q41. Your application needs to load a set of key value pairs from a database table which never changes. Multiple threads need to access this information but none of them changes it.

Which class would be the most appropriate to store such data if the values need not be kept in a sorted fashion?

Select 1 option(s):

Hashtable

HashMap

Set

TreeMap

List

Q42. Which of these statements are true?

Select 2 option(s):

A static method can call other non-static methods in the same class by using the 'this' keyword.

A class may contain both static and non-static variables and both static and non-static methods.

Each object of a class has its own copy of each non-static member variable.

Instance methods may access local variables of static methods.

All methods in a class are implicitly passed a 'this' parameter when called.

Q43. You have a collection (say, an ArrayList) which is read by multiple reader threads and which is modified by a single writer thread. The collection allows multiple concurrent reads but does not tolerate concurrent read and write. Which of the following strategies will you use to obtain best performance?

Select 1 option(s):

synchronize all access to the collection.

make the collection variable final.

make the collection variable final and volatile.

Wrap the collection into its synchronized version using Collections.synchronizedCollection().

Encapsulate the collection into another class and use ReadWriteLock to manage read and write access.

Use virtual threads instead of platform threads.

Q44. Which of these implementations for collection framework interfaces are provided in the standard JDK?

Select 3 option(s):

TreeMap

ArrayMap

HashSet

ArrayList

Q45. Given that TestClass is a class, how many objects and reference variables are created by the following code?

TestClass t1, t2, t3, t4;
t1 = t2 = new TestClass();
t3 = new TestClass();

Select 1 option(s):

2 objects, 3 references.

2 objects, 4 references.

3 objects, 2 references.

2 objects, 2 references.

None of the above.

Q46. You are implementing a special sorting algorithm that can sort objects of different classes. Which of the following class declarations will you use?

Select 1 option(s):

public class SpecialSorter< >{
...
}

public class SpecialSorter< K >{
...
}

public class < SpecialSorter >{
...
}

public class SpecialSorter(K){
...
}

Q47. Which of the following are true regarding the Date-Time API of java.time package?

Select 2 option(s):

It uses the calendar system defined in ISO-8601 as the default calendar.

Most of the actual date related classes in the Date-Time API such as LocalDate, LocalTime, and LocalDateTime are immutable.

LocalDateTime includes time zone information but LocalDate does not.

To create a LocalDate or a LocalDateTime object, you can use one of their several constructors.

Q48. What classes can a non-static nested class extend ?

(Provided that the class to be extended is visible and is not final.)

Select 1 option(s):

Only the encapsulating class.

Any top level class.

Any class.

It depends on whether the inner class is defined in a method or not.

None of the above.

Q49. Which of the following statements are correct?

Select 3 option(s):

An abstract class can be extended by an abstract or a concrete class.

A concrete class can be extended by an abstract or a concrete class.

An interface can be extended by another interface.

An interface can be extended by an abstract class.

An interface can be extended by a concrete class.

An abstract class cannot implement an interface.

Q50. Given:

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

Which of the following options correctly achieves the same or compatible declaration using type inference?

Select 2 option(s)

var stateCitiesMap = new HashMap< String, List< > >();

Map< String , List< ? extends CharSequence > > stateCitiesMap = new HashMap();

Map< String , List< ? extends CharSequence > > stateCitiesMap = new HashMap<>();

Map< String , List< ? extends CharSequence > > stateCitiesMap = new HashMap<<>>();

var stateCitiesMap = new HashMap< String, List< ? extends CharSequence > >();