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Linkedin Java Assessment

Offered By ”LinkedIn”

 

 

Q1. Given the string “strawberries” saved in a variable called fruit, what would fruit.substring(2, 5) return?
rawb
raw
awb
traw

Q2. How can you achieve runtime polymorphism in Java?
method overloading
method overrunning
method overriding
method calling

Q3. Given the following definitions, which of these expression will NOT evaluate to true?
boolean b1 = true, b2 = false; int i1 = 1, i2 = 2;

(i1 | i2) == 3
i2 && b1
b1 || !b2
(i1 ^ i2) < 4

Q4. What can you use to create new instances in Java?
constructor
another instance
field
private method

Q5. What is the output of this code?
1: class Main {
2: public static void main (String[] args) {
3: int array[] = {1, 2, 3, 4};
4: for (int i = 0; i < array.size(); i++) {
5: System.out.print(array[i]);
6: }
7: }
8: }

It will not compile because of line 4.
It will not compile because of line 3.
123
1234

Q6. Which of the following can replace the CODE SNIPPET to make the code below print “Hello World”?
interface Interface1 {
static void print() {
System.out.print(“Hello”);
}
}

interface Interface2 {
static void print() {
System.out.print(“World!”);
}
}
super1.print(); super2.print();
this.print();
super.print();
Interface1.print(); Interface2.print();

Q7. What does the following code print?
String str = “abcde”;
str.trim();
str.toUpperCase();
str.substring(3, 4);
System.out.println(str);
CD
CDE
D
“abcde”

Q8. What is the result of this code?
class Main {
public static void main (String[] args){
System.out.println(print(1));
}
static Exception print(int i){
if (i>0) {
return new Exception();
} else {
throw new RuntimeException();
}
}
}
It will show a stack trace with a runtime exception.
“java.lang.Exception”
It will run and throw an exception.
It will not compile.

Q9. Which class can compile given these declarations?

  •  D
class Three implements One, Two {
    public void method() {
        One.super.method();
    }
}

Q10. What is the output of this code?
class Main {
public static void main (String[] args) {
List list = new ArrayList();
list.add(“hello”);
list.add(2);
System.out.print(list.get(0) instanceof Object);
System.out.print(list.get(1) instanceof Integer);
}
}
The code does not compile.
truefalse
truetrue
falsetrue

Q11. Given the following two classes, what will be the output of the Main class?

Lines 1 and 2 generate compiler errors due to class name conflicts.
“-123”
It will throw an exception on line 5.
“123”

Q12. What is the result of this code?

It will not compile because of line 10.
“Hello!”
It will not compile because of line 2.
“World!”

Q13. Given this code, which command will output “2”?
class Main {
public static void main(String[] args) {
System.out.println(args[2]);
}
}
java Main 1 2 “3 4” 5
java Main 1 “2” “2” 5
java Main.class 1 “2” 2 5
java Main 1 “2” “3 4” 5

Q14. What is the output of this code?
class Main {
public static void main(String[] args){
int a = 123451234512345;
System.out.println(a);
}
}
“123451234512345”
Nothing – this will not compile.
a negative integer value
“12345100000”

Q15. What is the output of this code?
class Main {
public static void main (String[] args) {
String message = “Hello world!”;
String newMessage = message.substring(6, 12)
+ message.substring(12, 6);
System.out.println(newMessage);
}
}
The code does not compile.
A runtime exception is thrown.
“world!!world”
“world!world!”
String m = “Hello world!”;
String n = m.substring(6,12) + m.substring(12,6);
System.out.println(n);

Q16. How do you write a foreach loop that will iterate over ArrayList<Pencil>pencilCase?
for (Pencil pencil : pencilCase) {}
for (pencilCase.next()) {}
for (Pencil pencil : pencilCase.iterator()) {}
for (pencil in pencilCase) {}

Q17. Fill in the blanks?
Object-oriented programming (OOP) is a programming language model that organizes software design around (objects), rather than (actions).

Q18. What code would you use to tell if “schwifty” is of type String?
“schwifty”.getType() == String
“schwifty”.getClass().getSimpleName() == “String”
“schwifty”.getType().equals(“String”)
“schwifty” instanceof String

Q19. What does this code print?
System.out.print(“apple”.compareTo(“banana”));
0
positive number
negative number
compilation error

Q20. You have an ArrayList of names that you want to sort alphabetically. Which approach would NOT work?
names.sort(Comparator.comparing(String::toString))
Collections.sort(names)
names.sort(List.DESCENDING)
names.stream().sorted((s1, s2) -> s1.compareTo(s2)).collect(Collectors.toList())

Q21. By implementing encapsulation, you cannot directly access the class’s _ properties unless you are writing code inside the class itself.
private
protected
no-modifier
public

Q22. Which is the most up-to-date way to instantiate the current date?
new SimpleDateFormat(“yyyy-MM-dd”).format(new Date())
new Date(System.currentTimeMillis())
LocalDate.now()
Calendar.getInstance().getTime()

Q23. Fill in the blank to create a piece of code that will tell wether int0 is divisible by 5:
boolean isDivisibleBy5 = _____

int0 / 5 ? true: false
int0 % 5 == 0
int0 % 5 != 5
Math.isDivisible(int0, 5)

Q24. How many times will this code print “Hello World!”?
class Main {
public static void main(String[] args){
for (int i=0; i<10; i=i++){
i+=1;
System.out.println(“Hello World!”);
}
}
}
10 times
9 times
5 times
infinite number of times

Q25. The runtime system starts your program by calling which function first?
print
iterative
hello
main

Q26. What is the result of this code?
try{
System.out.print(“Hello World”);
}catch(Exception e){
System.out.println(“e”);
}catch(ArithmeticException e){
System.out.println(“e”);
}finally{
System.out.println(“!”)
}
It will throw a runtime exception
It will not compile
Hello World!
Hello World

Q27. Which statement is NOT true?
An anonymous class may specify an abstract base class as its base type.
An anonymous class does not require a zero-argument constructor.
An anonymous class may specify an interface as its base type.
An anonymous class may specify both an abstract class and interface as base types.

Q28. What will this program print out to the console when executed?
import java.util.LinkedList;

[5, 1, 10]
[10, 5, 1]
[1, 5, 10]
[10, 1, 5]

Q29. What is the output of this code?
class Main {
public static void main(String[] args){
String message = “Hello”;
for (int i = 0; i<message.length(); i++){
System.out.print(message.charAt(i+1));
}
}
}
“Hello”
A runtime exception is thrown.
The code does not compile.
“ello”

Q30. Object-oriented programming is a style of programming where you organize your program around __ rather than __ and data rather than logic.
functions; actions
objects; actions
actions; functions
actions; objects

Q31. What statement returns true if “nifty” is of type String?
“nifty”.getType().equals(“String”)
“nifty”.getType() == String
“nifty”.getClass().getSimpleName() == “String”
“nifty” instanceof String

Q32. What is the output of this code?
import java.util.*;
class Main {
public static void main(String[] args) {
List<Boolean> list = new ArrayList<>();
list.add(true);
list.add(Boolean.parseBoolean(“FalSe”));
list.add(Boolean.TRUE);
System.out.print(list.size());
System.out.print(list.get(1) instanceof Boolean);
}
}
A runtime exception is thrown.
3false
2true
3true

Q33. What is the result of this code?
1: class Main {
2: Object message(){
3: return “Hello!”;
4: }
5: public static void main(String[] args) {
6: System.out.print(new Main().message());
7: System.out.print(new Main2().message());
8: }
9: }
10: class Main2 extends Main {
11: String message(){
12: return “World!”;
13: }
14: }
It will not compile because of line 7.
Hello!Hello!
Hello!World!
It will not compile because of line 11.

Q34. What method can be used to create a new instance of an object?
another instance
field
constructor
private method

Q35. Which is the most reliable expression for testing whether the values of two string variables are the same?
string1 == string2
string1 = string2
string1.matches(string2)
string1.equals(string2)

Q36. Which letters will print when this code is run?
public static void main(String[] args) {
try {
System.out.println(“A”);
badMethod();
System.out.println(“B”);
} catch (Exception ex) {
System.out.println(“C”);
} finally {
System.out.println(“D”);
}
}
public static void badMethod() {
throw new Error();
}
A, B, and D
A, C, and D
C and D
A and D

Q37. What is the output of this code?
class Main {
static int count = 0;
public static void main(String[] args) {
if (count < 3) {
count++;
main(null);
} else {
return;
}
System.out.println(“Hello World!”);
}
}
It will throw a runtime exception.
It will not compile.
It will print “Hello World!” three times.
It will run forever.

Q38. What is the output of this code?
import java.util.*;
class Main {
public static void main(String[] args) {
String[] array = {“abc”, “2”, “10”, “0”};
List<String> list = Arrays.asList(array);
Collections.sort(list);
System.out.println(Arrays.toString(array));
}
}
[abc, 0, 2, 10]
The code does not compile.
[abc, 2, 10, 0]
[0, 10, 2, abc]

Q39. What is the output of this code?
class Main {
public static void main(String[] args) {
String message = “Hello”;
print(message);
message += “World!”;
print(message);
}
static void print(String message){
System.out.print(message);
message += ” “;
}
}
Hello World!
HelloHelloWorld!
Hello Hello World!
Hello HelloWorld!

Q40. What is displayed when this code is compiled and executed?
public class Main {
public static void main(String[] args) {
int x = 5;
x = 10;
System.out.println(x);
}
}
x
null
10
5

Q41. Which approach cannot be used to iterate over a List named theList?

  •  C
Iterator it = theList.iterator();
for (it.hasNext()) {
    System.out.println(it.next());
}

Q42. What method signature will work with this code?
boolean healthyOrNot = isHealthy(“avocado”);

public void isHealthy(String avocado)
boolean isHealthy(String string)
public isHealthy(“avocado”)
private String isHealthy(String food)

Q43. Which are valid keywords in a Java module descriptor (module-infoJava)?
provides, employs
imports, exports
consumes, supplies
requires, exports

Q44. Which type of variable keeps a constant value once it is assigned?
non-static
static
final
private

Q45. How does the keyword _volatile_ affect how a variable is handled?
It will be read by only one thread at a time.
It will be stored on the hard drive.
It will never be cached by the CPU.
It will be preferentially garbage collected.

Q46. What is the result of this code?
char smooch = ‘x’;
System.out.println((int) smooch);
an alphanumeric character
a negative number
a positive number
a ClassCastException

Q47. You get a NullPointerException. What is the most likely cause?
A file that needs to be opened cannot be found.
A network connection has been lost in the middle of communications.
Your code has used up all available memory.
The object you are using has not been instantiated.

Q48. How would you fix this code so that it compiles?
public class Nosey {
int age;
public static void main(String[] args) {
System.out.println(“Your age is: ” + age);
}
}
Make age static.
Make age global.
Make age public.
Initialize age to a number.

Q49. Add a Duck called “Waddles” to the ArrayList ducks.
public class Duck {
private String name;
Duck(String name) {}
}
Duck waddles = new Duck(); ducks.add(waddles);
Duck duck = new Duck(“Waddles”); ducks.add(waddles);
ducks.add(new Duck(“Waddles”));
ducks.add(new Waddles());

Q50. If you encounter UnsupportedClassVersionError it means the code was **\_** on a newer version of Java than the JRE **\_** it.
executed; interpreting
executed; compiling
compiled; executing
compiled, translating

Q51. Given this class, how would you make the code compile?
public class TheClass {
private final int x;

  •  D
private void setX(int x) {
    this.x = x;
}
public TheClass() {
    setX(77);
}

Q52. How many times f will be printed?
public class Solution {
public static void main(String[] args) {
for (int i = 44; i > 40; i–) {
System.out.println(“f”);
}
}
}
4
3
5
A Runtime exception will be thrown

Q53. Which statements about abstract classes are true?
1. They can be instantiated.
2. They allow member variables and methods to be inherited by subclasses.
3. They can contain constructors.
1, 2, and 3
only 3
2 and 3
only 2

Q54. Which keyword lets you call the constructor of a parent class?
parent
super
this
new

Q55. What is the result of this code?
1: int a = 1;
2: int b = 0;
3: int c = a/b;
4: System.out.println(c);
It will throw an ArithmeticException.
It will run and output 0.
It will not compile because of line 3.
It will run and output infinity.

Q56. Normally, to access a static member of a class such as Math.PI, you would need to specify the class “Math”. What would be the best way to allow you to use simply “PI” in your code?
Add a static import.
Declare local copies of the constant in your code.
This cannot be done. You must always qualify references to static members with the class form which they came from.
Put the static members in an interface and inherit from that interface.

Q57. Which keyword lets you use an interface?
extends
implements
inherits
import

Q58. Why are ArrayLists better than arrays?
You don’t have to decide the size of an ArrayList when you first make it.
You can put more items into an ArrayList than into an array.
ArrayLists can hold more kinds of objects than arrays.
You don’t have to decide the type of an ArrayList when you first make it.

Q59. Declare a variable that holds the first four digits of Π
int pi = 3.141;
decimal pi = 3.141;
double pi = 3.141;
float pi = 3.141;

Q60. Use the magic power to cast a spell
public class MagicPower {
void castSpell(String spell) {}
}
new MagicPower().castSpell(“expecto patronum”)
MagicPower magicPower = new MagicPower(); magicPower.castSpell();
MagicPower.castSpell(“expelliarmus”);
new MagicPower.castSpell();

Q61. What language construct serves as a blueprint containing an object’s properties and functionality?
constructor
instance
class
method

Q62. What does this code print?
public static void main(String[] args) {
int x=5,y=10;
swapsies(x,y);
System.out.println(x+” “+y);
}

static void swapsies(int a, int b) {
int temp=a;
a=b;
b=temp;
}
10 10
5 10
10 5
5 5

Q63. What is the result of this code?
try {
System.out.println(“Hello World”);
} catch (Exception e) {
System.out.println(“e”);
} catch (ArithmeticException e) {
System.out.println(“e”);
} finally {
System.out.println(“!”);
}
Hello World
It will not compile because the second catch statement is unreachable
Hello World!
It will throw runtime exception

Q64. What is not a java keyword
finally
native
interface
unsigned

Q65. Which operator would you use to find the remainder after division?
%
//
/
DIV

Q66. Which choice is a disadvantage of inheritance?
Overridden methods of the parent class cannot be reused.
Responsibilities are not evenly distributed between parent and child classes.
Classes related by inheritance are tightly coupled to each other.
The internal state of the parent class is accessible to its children.

Q67. Declare and initialize an array of 10 ints.
Array<Integer> numbers = new Array<Integer>(10);
Array[int] numbers = new Array[int](10);
int[] numbers = new int[10];
int numbers[] = int[10];

Q68. Refactor this event handler to a lambda expression:
groucyButton.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
System.out.println(“Press me one more time..”);
}
});
groucyButton.addActionListener(ActionListener listener -> System.out.println(“Press me one more time…”));
groucyButton.addActionListener((event) -> System.out.println(“Press me one more time…”));
groucyButton.addActionListener(new ActionListener(ActionEvent e) {() -> System.out.println(“Press me one more time…”);});
groucyButton.addActionListener(() -> System.out.println(“Press me one more time…”));

Q69. Which functional interfaces does Java provide to serve as data types for lambda expressions?
Observer, Observable
Collector, Builder
Filter, Map, Reduce
Consumer, Predicate, Supplier

Q69. What is a valid use of the hashCode() method?
encrypting user passwords
deciding if two instances of a class are equal
enabling HashMap to find matches faster
moving objects from a List to a HashMap

Q70. What kind of relationship does “extends” denote?
uses-a
is-a
has-a
was-a

Q71. How do you force an object to be garbage collected?
Set object to null and call Runtime.gc()
Set object to null and call System.gc()
Set object to null and call Runtime.getRuntime().runFinalization()
There is no way to force an object to be garbage collected Reference

Q72. Java programmers commonly use design patterns. Some examples are the __, which helps create instances of a class, the __, which ensures that only one instance of a class can be created; and the __, which allows for a group of algorithms to be interchangeable.
static factory method; singleton; strategy pattern
strategy pattern; static factory method; singleton
creation pattern; singleton; prototype pattern
singleton; strategy pattern; static factory method

Q73. Using Java’s Reflection API, you can use __ to get the name of a class and __ to retrieve an array of its methods.
this.getClass().getSimpleName(); this.getClass().getDeclaredMethods()
this.getName(); this.getMethods()
Reflection.getName(this); Reflection.getMethods(this)
Reflection.getClass(this).getName(); Reflection.getClass(this).getMethods()

Q74. What is a valid use of the hashCode() method?
moving objects from a List to a HashMap
deciding if two instances of a class are equal
enabling HashMap to find matches faster
encrypting user passwords

Q75. Which access modifier makes variables and methods visible only in the class where they are declared?
public
protected
nonmodifier
private

Q76. What type of variable can be assigned to only once?
private
non-static
final
static

Q77. How would you convert a String to an Int?
“21”.intValue()
String.toInt(“21”)
Integer.parseInt(“21”)
String.valueOf(“21”)

Q78. What method should be added to the Duck class to print the name Moby?
public class Duck {
private String name;

Duck(String name) {
this.name = name;
}

public static void main(String[] args) {
System.out.println(new Duck(“Moby”));
}
}
public String toString() { return name; }
public void println() { System.out.println(name); }
String toString() { return this.name; }
public void toString() { System.out.println(this.name); }

Q79. Which operator is used to concatenate Strings in Java
+
&
.

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