Java Test 18 - 2024

Welcome to your Java Test 18 - 2024

Name

Phone

Q1. Which import statements are required to compile the following code?

public class TestClass
{
public static void main(String[] args) throws Exception
{
LocalDate d = LocalDate.of(2020, 1, 2);
DateTimeFormatter df = DateTimeFormatter.ofPattern("yyyy MMM dd");
}
}

You had to select 2 option(s)

import java.date.*;

import java.util.*;

import java.time.*;

import java.time.format.*;

import java.text.*;

import java.util.date.*;

Q2. Which of the following is a legal return type of a method overriding the given method:

public Object myMethod() {...}

(Select the best option.)

You had to select 1 option(s)

Object

String

Return type can be any class since all objects can be cast to Object.

void

None of the above.

None

Q3. Given the following program, which one of these statements is true?

public class TestClass extends Thread
{
static Object lock1 = new Object();
static Object lock2 = new Object();
static volatile int i1, i2, j1, j2, k1, k2;
public void run()
{
while (true)
{
workWithLocks();
workWithoutLocks();
}
}
void workWithLocks()
{
synchronized(lock1) { i1++ ; i2++; }
synchronized(lock2) { k1++ ; k2++ ; }
j1++; j2++;
}
void workWithoutLocks()
{
if (i1 != i2) System.out.println("i");
if (j1 != j2) System.out.println("j");
if (k1 != k2) System.out.println("k");
}
public static void main(String args[])
{
new TestClass().start();
new TestClass().start();
}
}

You had to select 1 option(s)

The program will fail to compile.

One cannot be certain whether any of the letters i, j and k will be printed during execution.

One can be certain that none of the letters i, j and k will ever be printed during execution.

One can be certain that the letters i and k will never be printed during execution.

One can be certain that the letter k will never be printed during execution.

None

Q4. Given the following code, which statements are true?

class A{
int i;
}
class B extends A{
int j;
}

You had to select 3 option(s)

Class B extends class A.

Class B is the superclass of class A.

Class A inherits from class B.

Class B is a subclass of class A.

Objects of class B will always have a member variable named i .

Q5. Consider the following code written by a new developer:

while(true){
//additional valid code
if(isDone()) break;
}

What can be done to make this code more readable?

You had to select 1 option(s)

Use a for loop

Use the enhanced for loop

use do-while instead of while.

Use continue instead of break.

None

Q6. Which of the following interfaces can be used to execute a stored procedure on the database?

You had to select 1 option(s)

CallableStatement

PreparedStatement

ProceduralStatement

StoredStatement

None

Q7. Which of the following is correct regarding a HashSet?

You had to select 1 option(s)

Elements are stored in a sorted order.

It is immutable.

It only keeps unique elements.

Elements can be accessed using a unique key.

None

Q8. Which of the following are benefits of polymorphism?

You had to select 2 option(s)

It makes the code more reusable.

It makes the code more efficient.

It protects the code by preventing extension.

It makes the code more dynamic.

Q9. Which of the following statements are true?

You had to select 2 option(s)

Package member classes can be declared static.

Classes declared as members of top-level classes can be declared static.

Local classes can be declared static.

Anonymous classes cannot be declared static.

No type of class can be declared static.

Q10. True or false?

If you use a text block for creating a String, you cannot use escape sequences.

You had to select 1 option(s)

True

False

None

Q11. Which of the following methods does not return any value?

You had to select 1 option(s)

public doStuff() throws FileNotFoundException, IllegalArgumentException{
//valid code not shown
}

public null doStuff() throws FileNotFoundException, IllegalArgumentException{
//valid code not shown
}

public doStuff() {
return;
}

public void doStuff() throws FileNotFoundException, IllegalArgumentException{
//valid code not shown
return;
}

private doStuff() {
//valid code not shown
}

public var doStuff() {
int val = 10;
}

None

Q12. Given that a code fragment has just created a JDBC Connection and has executed an update statement, which of the following statements is correct?

You had to select 1 option(s)

Changes to the database are pending a commit call on the connection.

Changes to the database will be rolled back if another update is executed without commiting the previous update.

Changes to the database will be committed right after the update statement has completed execution.

Changes to the database will be committed when another query (update or select) is fired using the connection.

None

Q13. An instance member ...

You had to select 2 option(s)

can be a variable, a constant or a method.

is a variable or a constant.

belongs to the class.

belongs to an instance of the class.

is same as a local variable.

Q14. Which of the following standard functional interfaces returns a primitive type?

You had to select 1 option(s)

IntFunction

BiFunction

DoubleConsumer

Supplier

ToDoubleFunction

None

Q15. Given:

class Triangle{
public int base;
public int height;
public double area = 0;

public Triangle(int pBase, int pHeight){
this.base = pBase; this.height = pHeight;
updateArea();
}
public void updateArea(){
double a = base*height/2;
area = a;
}
public void setBase(int b){ base = b; updateArea(); }
public void setHeight(int h){ height = h; updateArea(); }
}

Which variables are not accessible from anywhere within given class code except from the scope in which they are declared?

You had to select 1 option(s)

base, height, area

area, b, h

base, height

b, h, a

None

Q16. Java Exceptions is a mechanism ..

You had to select 2 option(s)

for dealing with unexpected user inputs.

that you can use to determine what to do when something unexpected happens.

for logging unexpected behavior.

to ensure that the program runs even if something unexpected happens.

that the VM uses to exit the program when something unexpected happens.

Q17. Which of the following statements are correct regarding abstract classes and interfaces?

You had to select 2 option(s)

An abstract class can have private as well as static methods while an interface can not have static methods.

An abstract class cannot implement multiple interfaces while an interface can extend multiple interfaces.

Abstract classes can have abstract methods but interface cannot.

Abstract classes can have instance fields but interfaces can't.

An abstract class can have final methods but an interface cannot.

Q18. The closing delimiter of a Java text block is:

You had to 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

None

Q19. Identify the correct statements regarding JDBC.

You had to select 1 option(s)

The JDBC Driver must be loaded explicitly in the code before attempting to create a connection to the database.

Starting JDBC 4.0, the JDBC Driver class is not required any more.

Starting JDBC 4.0, the JDBC Driver class is not required to be loaded explicitly in the code any more.

JDBC 4.0 allows loading multiple JDBC Drivers while previous versions did not.

None

Q20. Which of the following are wrapper classes for primitive types?

You had to select 1 option(s)

java.lang.String

java.lang.Void

java.lang.Null

java.lang.Object

None of the above

None

Q21. Which of the following statements is/are true?

You had to select 1 option(s)

Subclasses must define all the abstract methods that the superclass defines.

A class implementing an interface must define all the methods of that interface.

A class cannot override the super class's constructor.

It is possible for two classes to be the superclass of each other.

An interface can implement multiple interfaces.

None

Q22. Using a break in a while loop causes the loop to break the current iteration and start the next iteration of the loop.

You had to select 1 option(s)

True

False

None

Q23. Given:

public class Employee{
String name;
public Employee(){
}
}

Which of the following lines creates an Employee instance?

You had to select 1 option(s)

Employee e;

Employee e = new Employee();

Employee e = Employee.new();

Employee e = Employee();

None

Q24. A try without resources statement must always have a ............. associated with it.

You had to select 1 option(s)

catch

throws

finally

catch or finally or both

throw

None

Q25. What will the following code print?

var rlock = new ReentrantLock();
var f1 = rlock.lock();
System.out.println(f1);
var f2 = rlock.lock();
System.out.println(f2);

You had to select 1 option(s)

true
true

true
false

true

It will not compile.

None

Q26. Consider the following code:

public class MyClass {

protected int value = 10;

}

Which of the following statements are correct regarding the field value?

You had to select 1 option(s)

It cannot be accessed from any other class.

It can be read but cannot be modified from any other class.

It can be modified but only from a subclass of MyClass.

It can be read and modified from any class within the same package.

None

Q27. Which of the following are true about the "default" constructor?

You had to select 2 option(s)

It is provided by the compiler only if the class does not define any constructor.

It initializes the instance members of the class.

It calls the no-args constructor of the super class.

It initializes instance as well as class fields of the class.

It is provided by the compiler if the class does not define a 'no-args' constructor.

Q28. What will the following code print?

You had to select 1 option(s)

abc

abcdef

def

It will print an empty string (or, in other words, nothing).

It will print an empty new line.

It will not compile because there is no concat ( ) method in String class.

None

Q29. Which of the following statements about an array are correct?

You had to select 2 option(s)

An array can dynamically grow in size.

Arrays can be created only for primitive types.

Every array has a built in property named 'size' which tells you the number of elements in the array.

Every array has an implicit method named 'length' which tells you the number of elements in the array.

Element indexing starts at 0.

All arrays can be cloned using clone method.

Q30. Which of these statements concerning the use of modifiers are true?

You had to select 1 option(s)

By default (i.e. no modifier) the member is only accessible to classes in the same package and subclasses of the class.

You cannot specify visibility of local variables.

Local variable always have default accessibility.

Local variables can be declared as private.

Local variables can only be declared as public.

None

Q31. Which of the following is/are valid double values for 10 million? (A million has 6 zeros)

You had to select 1 option(s)

double d = 10,000,000.0;

double d = 10-000-000;

double d = 10_000_000;

double d = 10 000 000;

None

Q32. Which of the following access control keywords can be used to enable all the subclasses to access a method defined in the base class?

You had to select 2 option(s)

public

private

protected

sealed

No keyword is needed.

Q33. Which of the following are valid standard country locale codes as returned by getCountry() method of Locale?

You had to select 3 option(s)

utf

UTF8

Q34. Which clause(s) are used by a module definition that implements a service?

You had to select 2 option(s)

exports

provides

uses

implements

requires

Q35. Which of the following options correctly create an ExecutorService instance?

You had to select 1 option(s)

var es = ExecutorService.getInstance();

var es = new ExecutorService();

var es = Executors.newFixedThreadPool(2);

var es = Executor.getSingleThreadExecutor();

var es = Executors.getSingleThreadExecutor();

None

Q36. What will the following code print?

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

var x = 1____3; //1

var y = 1_3; //2

var z = 3.234_567f; //3

System.out.println(x+" "+y+" "+z);
}
}

You had to select 1 option(s)

Compilation error at //1

Compilation error at //2

Compilation error at //3

Compilation error at //1 and //3

10003 103 3.234567

13 13 3.234567

None

Q37. Which of the following interfaces can be used to store a collection of non-duplicate/unique objects in an unordered fashion ?

You had to select 1 option(s)

List

Map

Set

SortedList

SortedSet

None

Q38. What is the correct declaration for an abstract method 'add' in a class that is accessible to any class, takes no arguments and returns nothing?

You had to select 1 option(s)

public void add();

abstract add();

abstract null add();

abstract public void add(){ }

abstract public void add() throws Exception;

None

Q39. Which of the following are true about a try/catch statement?

You had to select 1 option(s)

If it has multiple catch blocks, then they must be ordered from most specific exception to most generic exception.

A try (including a try with resources) block must have at least a catch or a finally block.

In a try-with-resources statement, the finally block is invoked before the resources are closed.

A try can have multiple finally blocks.

None

Q40. What will the following program print when run?

public class TestClass{
public static void main(String[] args){
try{
System.exit(0);
}
finally{
System.out.println("finally is always executed!");
}
}
}

You had to select 1 option(s)

It will print "finally is always executed!"

It will not compile as there is no catch block.

It will not print anything.

An exception will be thrown

None of the above.

None

Q41. Code that uses generic collection classes can interoperate with code that uses raw collections classes because of?

You had to select 1 option(s)

type erasure

reification

just in time compilation

byte code instrumentation

None

Q42. Identify correct statement(s) about Java records.

You had to select 3 option(s)

A record cannot define any instance field explicitly.

A record may define private instance fields explicitly.

A record may inherit fields and methods from an interface.

A record is not allowed to define instance fields and methods.

A record may have at most one varargs component.

A record must not implement the Serializable interface.

Q43. Which of the following standard functional interfaces is most suitable to process a large collection of int primitives and return processed data for each of them?

You had to select 1 option(s)

Function< Integer >

IntFunction

Consumer< Integer >

IntConsumer

Predicate< Integer >

None

Q44. Which one of the following is a valid definition of a class Car that cannot be sub-classed?

You had to select 1 option(s)

class Car { }

abstract class Car { }

native class Car { }

package p1;
static class Car { }

final class Car { }

sealed class Car { }

None

Q45. Which of these interfaces are in the Java Collections framework?

You had to select 4 option(s)

Set

Union

BitSet

Collection

Map

NavigableMap

Q46. Which of the following statements are true?

You had to select 2 option(s)

The extends keyword is used to specify inheritance.

subclass of a non-abstract class cannot be declared abstract.

subclass of an abstract class can be declared abstract.

subclass of a final class can be abstract.

A class, in which all the members are declared private, cannot be declared public.

Q47. Which of the following statements are true?

You had to select 3 option(s)

Q48. An overriding method must have a same parameter list and the same return type as that of the overridden method.

You had to select 1 option(s)

True

False

None

Q49. Which of the following statements concerning the switch statement construct are true?

You had to 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.

Q50. Which of these combinations of switch selector expression types and case label value types are legal within a switch statement?

Note: The switch statement transfers control to one of several statements or expressions,
depending on the value of an expression. This expression is called "switch selector expression".

switch ( Switch selector Expression ) SwitchBlock

You had to select 1 option(s)

switch selector expression of type int and case label value of type char.

switch selector expression of type float and case label value of type int.

switch selector expression of type byte and case label value of type float.

switch expression of type char and case label value of type byte.

switch selector expression of type boolean and case label value of type boolean.

None

Q51. Which variables declared in the encapsulating class or in the method, can an inner class access if the inner class is defined in a static method of encapsulating class?

You had to select 2 option(s)

All static variables

All final instance variables

All instance variables

All automatic variables.

All final or effectively final static or automatic variables

Q52. Consider the following code:

public class Conversion{
public static void main(String[] args){
int i = 1234567890;
float f = i;
System.out.println(i - (int)f);
}
}

What will it print when run?

You had to select 1 option(s)

It will print 0.

It will not print 0.

It will not compile.

It will throw an exception at runtime.

None of the above.

None

Q53. Identify the correct statements.

You had to select 1 option(s)

LocalDate, LocalTime, and LocalDateTime extend Date.

LocalDate, LocalTime, and LocalDateTime implement TemporalAccessor.

Both - LocalDate and LocalTime extend LocalDateTime, which extends java.util.Date.

LocalDate, LocalTime, and LocalDateTime implement TemporalAccessor and extend java.util.Date.

None

Q54. An anonymous class can be declared in a static method.

You had to select 1 option(s)

True

False

None

Q55. Which of the following statement(s) is/are correct?

You had to select 1 option(s)

An instance of java.time.Instant represents date and time as per the local time zone.

An instance of java.time.Instant represents time elapsed since Java epoch.

The date/time obtained using java.time.Instant.now() and using java.time.LocalDateTime.now() are same.

java.time.LocalDateTime contains local time zone information while java.time.Instant does not.

None

Time's up

Time is Up!