Java Foundation Test 5 – Java SE 21 1Z0-830 

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Welcome to your Foundation Test 5 – 2025

Name

Email

Phone

Q1. What will the following code print when compiled and run?

Select 1 option(s):

Compilation error at //1

Compilation error at //2

Compilation error at //3

Compilation error at //1 and //3

It will print WORLDhello

It will print WORLDHELLO

It will print HELLOWORLD

None

Q2. Identify the correct statements about ArrayList?

Select 3 option(s):

ArrayList extends java.util.AbstractList.

It allows you to access its elements in random order.

You must specify the class of objects you want to store in ArrayList when you declare a variable of type ArrayList.

ArrayList does not implement RandomAccess.

You can sort its elements using Collections.sort() method.

Q3. Given:

var al = new ArrayList();
al.forEach( k -> {
System.out.print(k.length());
});

Identify correct statements.

Select 1 option(s):

The type of k is Object.

The type of al is List< String >.

The type of al is List< Character >.

The code will not compile.

The code will compile but will throw an exception at run time.

The code will compile and run without any exception.

None

Q4. Which of these statements concerning maps are true?

Select 1 option(s):

It is permissible for a map to contain itself as a key.

values() method returns an instance of Set.

The Map interface extends the Collection interface.

All keys in a map are unique.

All Map implementations keep the keys sorted.

None

Q5. Which of the following interface definitions can be implemented using lambda expressions?

Select 1 option(s):

interface A{
}

@FunctionalInterface
interface A{
default void m(){};
}

interface A{
void m(){};
}

interface A{
default void m1(){};
void m2();
}

@FunctionalInterface
interface A{
void m1();
void m2();
}

None

Q6. Which of the following code fragments will NOT cause a compilation error when put inside the following code?

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

//INSERT CODE HERE

}
}

Select 2 option(s):

var m = 20;
m = "20";

var list = new ArrayList<>();
list.add(20);
list.add("20");

var ex = new Exception();
ex = new java.io.IOException();

var str = null;

Runnable r = new Runnable(){
var str = "hello";
public void run(){
System.out.println(str);
}
};

var list = new ArrayList<>();
list.add("20");
String str = list.get(0);

class Rule{
var id = 10;
}

var _ = """
hello
hi""";

Q7. Identify the correct statements about ArrayList?

Select 3 option(s):

Standard JDK provides no subclasses of ArrayList.

An ArrayList cannot store primitives.

It allows constant time access to all its elements.

ArrayList cannot resize dynamically if you add more number of elements than its capacity.

An ArrayList is backed by an array.

Q8. Given:

String[] p = {"1", "2", "3" };

Which of the following lines of code is/are valid?

Select 1 option(s):

List< ? > list2 = new ArrayList< Integer >(Arrays.asList(p));

List< Integer > list2 = new ArrayList< Integer >(Arrays.asList(p));

List< Integer > list2 = new ArrayList< >(Arrays.asList(p));

List< ? > list2 = new ArrayList< >(Arrays.asList(p));

None

Q9. Assume that a method named 'method1' contains code which may raise a non-runtime (i.e. a checked) exception.

What is/are the possible way(s) to declare this method so that it indicates that it expects the caller to handle that exception?

Select 2 option(s):

public void method1() throws Throwable

public void method1() throw Exception

public void method1() throw new Exception

public void method1() throws Exception

public void method1()

Q10. Which of the following are valid?

(Assume the method bodies are valid.)

Select 3 option(s):

BiFunction< Integer, Integer, Double > bf = (a, b)->a/b;

public BiFunction< Integer, String, Double > getBF(){ ... }

class Transformer< T >{
public BiFunction< T, T, T > getMethod(){ ... }
}

BiFunction< int, int, int > bf = (a, b)->a/b;

< A, B, C > BiFunction< A, B, C > predicate(Function< A, B > f){ ... }

Q11. Which of the following declarations is equivalent to var b = 10>11;.

Select 2 option(s):

bool b = false;

var b = false;

var b = false|true;

bool b = (10<11);

boolean b = false;

Q12. Which of the following are benefits of ArrayList over an array?

Select 1 option(s):

You do not have to worry about the size of the ArrayList while appending elements.

It consumes less memory space.

You do not have to worry about thread safety.

It allows you to write type safe code.

None

Q13. Which of the following lambda expressions can be used to invoke a method that accepts a java.util.function.Predicate as an argument?

Select 2 option(s):

x -> System.out.println(x)

x -> System.out.println(x);

x -> x == null

() -> true

x->true

Q14. What can be inserted at line 2 in the code snippet given below?

String[] names = {"Alex", "Bob", "Charlie" };
//Insert code here
System.out.println(list.get(0));

Select 2 option(s):

List< ? > list = new ArrayList< >(Arrays.asList(names));

List< String > list = new ArrayList< >(Arrays.asList(names));

List< ? > list = new ArrayList< ? >(Arrays.asList(names));

List<> list = new ArrayList< String >(Arrays.asList(names));

Q15. Consider the following lines of code:

System.out.println(null + true); //1
System.out.println(true + null); //2
System.out.println(null + null); //3

Which of the following statements are correct?

Select 1 option(s):

None of the 3 lines will compile.

All the 3 lines will compile and print nulltrue, truenull and nullnull respectively.

Line 1 and 2 won't compile but line 3 will print nullnull.

Line 3 won't compile but line 1 and 2 will print nulltrue and truenull respectively.

None of the above.

None

Q16. Consider the standard 'put' method of class HashMap.

public Object put(Object key, Object value);

Select 1 option(s):

It always returns null.

It always returns value ( i.e. the 2nd parameter).

Neither of key or value can be null otherwise a NullPointerException is thrown.

Key cannot be null but value may be null.

It may throw a DuplicateKeyException.

None of these.

None

Q17. Identify correct option(s):

Note: The options are not about Java but about OOP in general.

Select 2 option(s):

Multiple inheritance of state includes ability to inherit instance methods from multiple classes.

Multiple inheritance of state includes ability to inherit instance fields from multiple classes.

Multiple inheritance of type includes ability to inherit instance fields as well as instance methods from multiple classes.

Multiple inheritance of type includes ability to implement multiple interfaces and ability to inherit static or instance fields from interfaces and/or classes.

Multiple inheritance of type includes ability to implement multiple interfaces and/or ability to extend from multiple classes.

Q18. Which of the following statements will compile without any error?

Select 3 option(s):

List< ? super Float > a = new ArrayList< Float >();

List< ? super Float > b = new ArrayList< Double >();

List< ? super Number > c = new ArrayList< Integer >();

List< ? extends Number > d = new ArrayList< Number >();

List< ? extends Number > e = new ArrayList< Float >();

List< ? extends Number > f = new ArrayList< Object >();

Q19. Which of the following are valid ways to create a LocalDateTime instance?

Select 1 option(s):

java.time.LocalDate.parse("2015-01-02");

java.time.LocalDateTime.parse("2015-01-02");

java.time.LocalDateTime.of(2015, 10, 1, 10, 10);

java.time.LocalDateTime.of(2015, "January", 1, 10, 10);

None

Q20. An existing application contains the following code:

interface AmountValidator{
public boolean checkAmount(double value);
}
public class Account {
public void updateBalance(double bal ){

boolean isOK = new AmountValidator(){
public boolean checkAmount(double val){
return val >= 0.0;
}
}.checkAmount(bal);

//other irrelevant code
}
}

Which interface from java.util.function package should be used to refactor this code?

Select 1 option(s):

Consumer

Function

Predicate

Supplier

None

Q21. Which of the following expressions can be used to implement a Function ?

Select 3 option(s):

(a)-> Integer.toHexString(a)

a -> Integer::toHexString

Integer::toHexString

i::toHexString
(Assume that i is a reference to an Integer object.)

toHexString

val -> val + 1

(Integer a)-> Integer.toHexString(a)

Integer a-> Integer.toHexString(a)

Q22. Given:

record Student(int id, String name) {
}

Which of the following methods will be added automatically to this record?

Select 3 option(s):

public String getName(){ return name; }

public setName(String name){ this.name = name; }

public final boolean equals(Object)

public final int hashCode()

public final String toString()

Q23. Given:

interface Runner {
public void run();
}

Which of the following is/are valid lambda expression(s) that capture(s) the above interface?

Select 2 option(s):

-> System.out.println("running...");

void -> System.out.println("running...")

() -> System.out.println("running...")

() -> { System.out.println("running..."); return; }

(void) -> System.out.println("running...")

-> System.out.println("running...")

Q24. Given:

public record Student(int id) {
}

What is inserted by the compiler automatically in this record?

Select 3 option(s):

Canonical constructor

A toString method.

A clone method.

An equals method.

A getId method.

A zero-argument/no-args constructor.

Q25. Which of the following lambda expressions can be used to implement a Function ?

Select 1 option(s):

(a)-> 2*a

(a, s)-> a+" "+s

(s) ->"hello "+s+"!"

(a, s, r)-> a+" "+s

(a)-> System.out.println("done")

None

Q26. What will the following program print?

public class TestClass{
public static void main(String[] args){
Object obj1 = new Object();
Object obj2 = obj1;
if( obj1.equals(obj2) ) System.out.println("true");
else System.out.println("false");
}
}

Select 1 option(s):

true

false

It will not compile.

It will compile but throw an exception at run time.

None of the above.

None

Q27. Which functional interface(s) would you use if you need a function that always returns the same type as the type of its input(s)?

Select 2 option(s):

Function

UnaryOperator

Supplier

Predicate

BinaryOperator

Consumer

BiConsumer

Q28. Given:

HashMap hm = new HashMap();
hm.put(1, "a"); hm.put(2, "b"); hm.put(3, "c");

Which of the following statements will print the keys as well as values contained in the map?

Select 1 option(s):

hm.forEach((key, entry)->System.out.println(entry));

hm.forEach(System.out.println("%d %s"));

hm.forEach((key, value)->System.out.printf("%d %s ", key, value));

hm.forEach(System.out::println);

hm.forEach(entry->System.out.println(entry));

None

Q29. Given:

BiFunction bf
= (String s, Integer i) -> { return s.substring(0, i); };

What of the following lambda expressions is equivalent to the one used above?

Select 1 option(s):

(s, i)->s.substring(0, i)

(s, i)->s::substring(0, i)

(s, i)->s:substring(0, i)

s::substring(0, i)

None

Q30. What will be printed by the following code if it is run with command line: java TestClass -0.50 ?

public class TestClass{
public static double getSwitch(String str){
return Double.parseDouble(str.substring(1, str.length()-1) );
}
public static void main(String args []){
switch(getSwitch(args[0])){
case 0.0 -> System.out.println("Hello");
case 1.0 -> { System.out.println("World"); break; }
default -> System.out.println("Good Bye");
}
}
}

Select 1 option(s):

Hello

World

Hello World

Hello World Good Bye

The code will not compile because the type of the switch selector expression is invalid.

The code will not compile because the usage of break is invalid.

None

Q31. Given :

import java.util.*;
class MyStringComparator implements Comparator
{
public int compare(Object o1, Object o2)
{
int s1 = ((String) o1).length();
int s2 = ((String) o2).length();
return s1 - s2;
}
}
and

static String[] sa = { "d", "bbb", "aaaa" };

Select correct statements.

Select 2 option(s):

This is not a valid Comparator implementation.

Arrays.binarySearch(sa, "cc", new MyStringComparator()); will return -2.

Arrays.binarySearch(sa, "c", new MyStringComparator()); will return 0.

Arrays.binarySearch(sa, "c", new MyStringComparator()); will return -1.

Arrays.binarySearch(sa, "c", new MyStringComparator()); will throw an exception.

Q32. What is the result of executing the following code when the value of i is 5:

switch (i){
default:
case 1:
System.out.println(1);
case 0:
System.out.println(0);
case 2:
System.out.println(2);
break;
case 3:
System.out.println(3);
}

Select 1 option(s):

It will print 1 0 2

It will print 1 0 2 3

It will print 1 0

It will print 1

Nothing will be printed.

None

Q33. Which of the following statements concerning the switch statement with or without pattern matching construct are true?

Select 3 option(s):

A character literal can be used as a value for a case label.

A 'long' cannot be used as a switch variable.

An empty switch block is a valid construct.

A switch block must have a default label.

If present, the default label must be the last of all the labels.

Q34. Identify correct statements about virtual threads.

Select 3 option(s):

VirtualThread is a Thread.

It is not possible to directly refer to the VirtualThread class in Java code.

A Virtual thread is never a daemon thread.

Thread is a VirtualThread.

Virtual threads are light weight as compared to regular threads.

Q35. You are designing a class that will cache objects. It should be able to store and retrieve an object when supplied with an object identifier.

Further, this class should work by tracking the "last accessed times" of the objects. Thus, if its capacity is full, it should remove only the object that hasn't been accessed the longest.

Which collection class would you use to store the objects?

Select 1 option(s):

HashSet

ArrayList

LinkedHashMap

LinkedList

TreeMap

None

Q36. Which of the following are valid operators in Java?

Select 5 option(s):

!

~

&

%=

$

^

Q37. Consider the following class:

public class Test{
public int id;
}

Which of the following is the correct way to make the variable 'id' read only for any other class?

Select 1 option(s):

Make 'id' private.

Make 'id' private and provide a public method getId() which will return its value.

Make 'id' static and provide a public static method getId() which will return its value.

Make id 'protected'

None

Q38. Identify potentially valid declarations of a sealed class.

Select 4 option(s):

public abstract sealed class DocType { }

public sealed class DocType { }

public abstract sealed class DocType permits Pdf, Doc { }

public sealed class DocType implements Readable permits Pdf, Doc { }

final sealed class DocType permits Pdf, Doc{ }

Q39. Which line contains a valid constructor in the following class definition?

public class TestClass{
int i, j;
public TestClass getInstance() { return new TestClass(); } //1
public void TestClass(int x, int y) { i = x; j = y; } //2
public TestClass TestClass() { return new TestClass(); } //3
public ~TestClass() { } //4
}

Select 1 option(s):

Line 1

Line 2

Line 3

Line 4

None of the above.

None

Q40. Identify correct statement(s) about Java records.

Select 1 option(s):

A record can have exactly one constructor provided explicitly by the programmer.

A record may have at most one compact and one non-compact constructor.

A record may have at most one compact and one normal canonical constructor.

A record may have any number of overloaded constructors.

None

Q41. Compared to public, protected, and private accessibilities, default accessibility is....

Select 1 option(s):

Less restrictive than public.

More restrictive than public, but less restrictive than protected.

More restrictive than protected, but less restrictive than private.

More restrictive than private.

Less restrictive than protected from within a package, and more restrictive than protected from outside a package.

None

Q42. Which of the following statements are true?

Select 3 option(s):

Non-static nested classes must have either default or public accessibility.

Non-static nested classes cannot contain static members.

Methods in all nested classes can be declared static.

All nested classes can be declared static.

A static nested class can contain a non - static inner class.

A nested class may be sealed.

Q43. Which of the following statements are true?

Select 1 option(s):

A synchronized method cannot call another synchronized method in its body.

Making a synchronized method recursive will cause a deadlock.

Only non-static member variables are accessible in a synchronized method.

A synchronized method cannot be executed simultaneously by more than one thread on the same object.

A synchronized method cannot call a non-synchronized method in its body.

None

Q44. Which of the following statements are true?

Select 1 option(s):

For any non-null reference o1, the expression (o1 instanceof o1) will always yield true.

For any non-null reference o1, the expression (o1 instanceof Object) will always yield true.

For any non-null reference o1, the expression (o1 instanceof o1) will always yield false.

For any non-null reference o1, the expression (o1 instanceof Object) may yield false.

None of the above.

None

Q45. Which line in the following code will cause the compilation to fail?

public class TestClass {

public static void main(String[] args) throws Exception {
work(); //LINE 10
int j = j1; //LINE 11
int j1 = (double) x; //LINE 12
}

public static void work() throws Exception{
System.out.println(x); //LINE 15
}

static double x; //19
}

Select 2 option(s):

Line 10

Line 11

Line 12

Line 15

Line 19

Q46. What will be printed when the following code is compiled and run?

public class LoadTest{

public static void main(String[] args) throws Exception {
LoadTest t = new LoadTest();
int i = t.getLoad();
double d = t.getLoad();
System.out.println( i + d );
}

public int getLoad() {
return 1;
}

public double getLoad(){
return 3.0;
}

}

Select 1 option(s):

13.0

4.0

4

The code will not compile.

None

Q47. What will the following program print when compiled and run:

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

static void someMethod(Object parameter) {
System.out.println("Value is "+parameter);
}
}

Select 1 option(s):

It will not compile.

Value is null

Value is

It will throw a NullPointerException at run time.

None

Q48. Given:

class Base{
public Collection getCollection(T t, Integer n)
{
return new ArrayList();
}
}

class Derived extends Base{

//public List getCollection(T t, Integer m){ return new ArrayList(); }; //1

//public Stream getCollection(T t, Integer m){ return new ArrayList(); }; //2

//public void getCollection(T t, Integer m){ return new ArrayList(); }; //3

//public List getCollection(String t, Integer m){ return new ArrayList(); };//4
}


Identify correct statements about the methods defined in Derived assuming they are uncommented one at a time individually.

Select 1 option(s):

//1, //2, and //3 correctly override the method in Base.

//2, //3, and //4 correctly overload the method in Base

//2 and //3 correctly override the method in Base.

//1 correctly overloads while //4 correctly overrides the method in Base.

//1 correctly overrides the method in Base.

//1 and //4 cannot be inserted in the code at the same time.

None

Q49. 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();
}
}

Select 1 option(s):

test

new test

It will not compile.

It will throw an exception at run time.

None

Q50. Which of the following statements regarding java.util.HashSet is correct?

Select 1 option(s):

It keeps the elements in a sorted order.

It allows duplicate elements because it is based on HashMap.

It stores name-value pairs.

The order of elements seen while iterating through a HashSet always remains same.

It allows null value to be stored.

None

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