Java Test 22 – 2024

Q1. Given:

package loops;
public class JustLooping {
private int j;
void showJ(){
while(j<=5){
for(int j=1; j <= 5;){
System.out.print(j+" ");
j++;
}
j++;
}
}
public static void main(String[] args) {
new JustLooping().showJ();
}
}

What is the result?

You had to select 1 option(s)

Q2. Given the following code for Book class:

record Book(String title, String isbn){
//insert code here
}

What of the following options illustrates correct usage of instanceof with pattern matching?

You had to select 1 option(s)

Q3. Consider the following code :

public class TestClass extends Thread
{
class Runner implements Runnable
{
public void run()
{
var t = new Thread[5];
for(int i=0; i<t.length; i++) System.out.println(t[i]);
}
}

public static void main(String args[]) throws Exception
{
var tc = new TestClass();
new Thread( tc.new Runner() ).start();
}
}

How many Thread objects are created by the above program when it is compiled and run?

You had to select 1 option(s)

Q4. Consider the following code:

class A {
public void doA(int k) throws Exception { // 0
for(int i=0; i< 10; i++) {
if(i == k) throw new Exception("Index of k is "+i); // 1
}
}
public void doB(boolean f) { // 2
if(f) {
doA(15); // 3
}
else return;
}
public static void main(String[] args) { // 4
A a = new A();
a.doB(args.length>0); // 5
}
}

Which of the following statements are correct?

You had to select 1 option(s)

Q5. Given that Book is a valid class with appropriate constructor and getPrice method that returns a double, what can be inserted at //1 so that it will sum the price of all the books that are priced greater than 5.0?

List books = Arrays.asList(
new Book("Gone with the wind", 10.0),
new Book("Atlas Shrugged", 10.0),
new Book("Freedom at Midnight", 5.0),
new Book("Gone with the wind", 5.0)
);

//1 INSERT CODE HERE

System.out.println(sum);

You had to select 2 option(s)

Q6. What will the following code print?

public class Test{
public int luckyNumber(int seed){
if(seed > 10) return seed%10;
int x = 0;
try{
if(seed%2 == 0) throw new Exception("No Even no.");
else return x;
}
catch(Exception e){
return 3;
}
finally{
return 7;
}
}

public static void main(String args[]){
int amount = 100, seed = 6;
switch( new Test().luckyNumber(6) ){
case 3: amount = amount * 2;
case 7: amount = amount * 2;
case 6: amount = amount + amount;
default :
}
System.out.println(amount);
}
}

You had to select 1 option(s)

Q7. What will the following code print?

public class BreakTest{
public static void main(String[] args){
int i = 0, j = 5;
lab1 : for( ; ; i++){
for( ; ; --j) if( i >j ) break lab1;
}
System.out.println(" i = "+i+", j = "+j);
}
}

You had to select 1 option(s)

Q8. Consider the following code to count objects and save the most recent object:

int i = 0 ;
Object prevObject ;
public void saveObject(List e ){
prevObject = e ;
i++ ;
}

Which of the following calls will work without throwing an exception?

You had to select 3 option(s)

Q9. What changes can be done to the following code so that it will compile and run without an exception?

List keys = List.of("a"); //1
keys.add("b"); //2

Map map = Map.of(); //3

int i = 0;
for(var key : keys){
map.put(key, "----");
}
System.out.println(keys+" "+map.size());

You had to select 1 option(s)

Q10. Given the following contents of module-info.java,

module enthu.finance{
exports com.enthu.Reports to com.enthu.tax;
requires transitive enthu.utils;
}

Select correct statements.

You had to select 1 option(s)

Q11. Given:

public List getList(){
*INSERT CODE HERE*
}


What can be inserted in the above code?

You had to select 3 option(s)

Q12. You have been given an array of objects and you need to process this array as follows -

1. Call a method on each object from first to last one by one.
2. Call a method on each object from last to first one by one.
3. Call a method on only those objects at even index (0, 2, 4, 6, etc.)

Which of the following are correct?

You had to select 1 option(s)

Q13. Which of the given lines can be inserted at //1 of the following program ?

public class TestClass
{
public static void main(String[] args)
{
short s = 9;
//1
}

}

You had to select 2 option(s)

Q14. What, if anything, is wrong with the following code?

interface T1{
}
interface T2{
int VALUE = 10;
void m1();
}

interface T3 extends T1, T2{
public void m1();
public void m1(int x);
}

You had to select 1 option(s)

Q15. Consider the following code:

class A
{
}
public class TestClass
{
public class A
{
public void m() { }
}
class B extends A
{
B(){ m(); }
}
public static void main(String args[])
{
new TestClass().new A() { public void m() { } }; //1
var tc = new TestClass();
//insert call to A's m() here
}
}

You had to select 4 option(s)

Q16. 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", null);
DoubleSupplier ds1 = b1::getPrice;
System.out.println(b1.getTitle()+" "+ds1.getAsDouble());

You had to select 1 option(s)

Q17. Given:

module broker{
exports org.broker.api;
}

The broker module contains org.broker.api.Installer interface, which is implemented by com.foo.AppInstaller class of com.foo module.

Which of the following is a valid module definition for com.foo module?

You had to select 1 option(s)

Q18. The following are complete contents of TestClass.java:

class Book{
protected final int pages = 100;
final void mA(){
System.out.println("In B.mA "+pages);
}
}

class Encyclopedia extends Book{
private int pages = 200; //1
void mB(){
System.out.println("In E.mB "+pages);
}
void mA(){ //2
System.out.println("In E.mA "+pages);
}
}
public class TestClass {
public static void main(String[] args) {
Book o1 = new Encyclopedia (); //3
Book o2 = new Book();
o1.mA(); //4
o1.mB(); //5
o2.mA();
}
}

Which lines will cause compilation to fail?

You had to select 1 option(s)

Q19. Given:

int expr1 = 3 + 5 * 9 - 7;
int expr2 = 3 + (5 * 9) - 7;
int expr3 = 3 + 5 * (9 - 7);
int expr4 = (3 + 5) * 9 - 7;


Which of the above variables will have the value 45?

You had to select 1 option(s)

Q20. Given the following command:

javac --module-source-path c:\java\a -d c:\java\b -p c:\java\c -m x.y

Which of the following statements are correct?

You had to select 1 option(s)

Q21. Given:

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

public Triangle(int base, int height){
this.base = base; this.height = height;
updateArea();
}

void updateArea(){
area = base*height/2;
}
public void setBase(int b){ base = b; updateArea(); }
public void setHeight(int h){ height = h; updateArea(); }
}
The above class needs to protect an invariant on the "area" field (meaning, the value of the ///area/// field should always be equal to the value computed using the formula for area of a triangle). Which three members must have the public access modifiers removed to ensure that the invariant is maintained?

You had to select 3 option(s)

Q22. What will the following code print?

int[] a = { 'h', 'e', 'l'};
int[] b = { 'h', 'e', 'l', 'l', 'o'};

int x = Arrays.compare(a, b);
int y = Arrays.mismatch(a, b);
System.out.println(x+" "+y);

You had to select 1 option(s)

Q23. What will the following code print when compiled and run?

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

String s = "blooper";
StringBuilder sb = new StringBuilder(s);
s.append("whopper");
sb.append("shopper");

System.out.println(s);
System.out.println(sb);
}
}

You had to select 1 option(s)

Q24. Identify correct statement(s) about the following code:

var value = 1,000,000; //1
switch(value){
case 1_000_000 - > { //2
System.out.println("A million 1");
break; //3
}
case 1000000 - > { //4
System.out.println("A million 2");
}
}

You had to select 1 option(s)

Q25. Consider the following code:

public class FileCopier {
public static void copy(String records1, String records2) throws IOException {
try (
InputStream is = new FileInputStream(records1);
OutputStream os = new FileOutputStream(records2);) {
byte[] buffer = new byte[1024];
int bytesRead = 0;
while ((bytesRead = is.read(buffer)) != -1) {
os.write(buffer, 0, bytesRead);
System.out.println("Read and written bytes " + bytesRead);
}
} catch (IOException | IndexOutOfBoundsException e) {
e = new FileNotFoundException();
e.printStackTrace();
}
}

public static void main(String[] args) throws Exception {
copy("c:\\temp\\test1.txt", "c:\\temp\\test2.txt");
}
}

Assuming appropriate import statements and the existence of both the files, what will happen when the program is compiled and run?

You had to select 1 option(s)

Q26. What will the following code print when run?

public class Test{
static String j = "";
public static void method( int i){
try{
if(i == 2){
throw new Exception();
}
j += "1";
}
catch (Exception e){
j += "2";
return;
}
finally{
j += "3";
}
j += "4";
}
public static void main(String args[]){
method(1);
method(2);
System.out.println(j);
}
}

You had to select 1 option(s)

Q27. What will the following code print?

Path p1 = Paths.get("/photos/vacation");
Path p2 = Paths.get("/yellowstone");
System.out.println(p1.resolve(p2)+" "+p1.relativize(p2));

You had to select 1 option(s)

Q28. Given the following class, which statements can be inserted at line 1 without causing the code to fail compilation?

public class TestClass{
int a;
int b = 0;
static int c;
public void m(){
int d;
int e = 0;
// Line 1
}
}

You had to select 4 option(s)

Q29. Given:

List dList = Arrays.asList(10.0, 12.0);
dList.forEach(x->{ x = x + 10; });
dList.forEach(x->System.out.println(x));

What will it print when compiled and run?

You had to select 1 option(s)

Q30. Given the following method code:

public void myMethod() throws MyException {

//method code

}

You had to select 1 option(s)

Q31. Which of the following commands can be used to run a class named com.foo.Bar, which is part of a module named foo.bar packaged in foobar.jar

(Assume that the jar file is located in the current directory.)

You had to select 1 option(s)

Q32. What will the following code print when compiled and run?

(Assume that MySpecialException is an unchecked exception.)

1. public class ExceptionTest {
2. public static void main(String[] args) {
3. try {
4. doSomething();
5. } catch (MySpecialException e) {
6. System.out.println(e);
7. }
8. }
9.
10. static void doSomething() {
11. int[] array = new int[4];
12. array[4] = 4;
13. doSomethingElse();
14. }
15.
16. static void doSomethingElse() {
17. throw new MySpecialException("Sorry, can't do something else");
18. }
}

You had to select 1 option(s)

Q33. What will the following code print?

List str = Arrays.asList(1,2, 3, 4 );
str.stream().filter(x->{
System.out.print(x+" ");
return x>2;
});

You had to select 1 option(s)

Q34. The following code snippet will print true.

String str1 = "one";
String str2 = "two";
System.out.println( str1.equals(str1=str2) );

You had to select 1 option(s)

Q35. Given:

public class Book {
private int id;
private String title;
private String genre;
private String author;
private double price;

//constructors and accessors not shown
}

Assuming that books is a List of Book objects, what can be inserted in the code below at DECLARATION and EXPRESSION so that it will classify the books by genre and then also by author?

DECLARATION classified = null;
classified = books.stream().collect(Collectors.groupingBy(
EXPRESSION
));
System.out.println(classified);

You had to select 1 option(s)

Q36. Given:

StringBuilder sb = new StringBuilder("asdf");

Which of the following code fragments will print true?

You had to select 1 option(s)

Q37. Given:

class OverloadingTest{

void m1(int x){
System.out.println("m1 int");
}

void m1(float x){
System.out.println("m1 float");
}

void m1(String x){
System.out.println("m1 String");
}

}

public class TestClass {
public static void main(String[] args) throws Exception {
OverloadingTest ot = new OverloadingTest();
ot.m1(1.0);
}
}

What will be the output?

You had to select 1 option(s)

Q38. Consider the following

public class TestClass {
public static void main(String[] args) {
TestClass tc = new TestClass();
tc.myMethod();
}

public void myMethod() {
yourMethod();
}

public void yourMethod() {
throw new Exception();
}
}

What changes can be done to make the above code compile?

You had to select 1 option(s)

Q39. What will be the result of compiling and running the following program ?

class NewException extends Exception {}
class AnotherException extends Exception {}
public class ExceptionTest{
public static void main(String [] args) throws Exception{
try{
m2();
}
finally{ m3(); }
}
public static void m2() throws NewException{ throw new NewException(); }
public static void m3() throws AnotherException{ throw new AnotherException(); }
}

You had to select 1 option(s)

Q40. Given:

abstract class Vehicle{ }
interface Drivable{ }
class Car extends Vehicle implements Drivable{ }
class SUV extends Car { }

Which of the following options will compile?

You had to select 2 option(s)

Q41. Identify valid methods:

Assume that Shape is a valid non-final class.

You had to select 2 option(s)

Q42. What will the following code most likely print when compiled and run?

List names = Arrays.asList("greg", "dave", "don", "ed", "fred" );
Map data = names.stream().collect(Collectors.groupingBy(
String::length,
Collectors.counting()) );
System.out.println(data.values());

You had to select 1 option(s)

Q43. Assume that dt refers to a valid java.util.Date object and that df is a reference variable of class DateFormat.

Which of the following code fragments will print the country and the date in the correct local format?

You had to select 1 option(s)

Q44. Given that c:\temp\pathtest is a directory that contains several directories. Each sub directory contains several files but there is exactly one regular file named test.txt within the whole directory structure.

Which of the given options can be inserted in the code below so that it will print complete path of test.txt?

try{
Stream s = null;

INSERT CODE HERE

s.forEach(System.out::println);
}catch(IOException ioe){
ioe.printStackTrace();
}

You had to select 1 option(s)

Q45. Given the following source code, which of the lines that are commented out may be reinserted without introducing errors?

abstract class Bang{
// abstract void f(); // LINE 0
final void g(){}
// final void h(){} // LINE 1
protected static int i;
private int j;
}

final class BigBang extends Bang{
// BigBang(int n) { m = n; } // LINE 2
public static void main(String args[]){
Bang mc = new BigBang();
}
// @Override // LINE 3
void h(){}
// void k(){ i++; } // LINE 4
// void l(){ j++; } // LINE 5
int m;
}

Consider each line independently.

You had to select 1 option(s)

Q46. Given:

What will be the result?

You had to select 1 option(s)

Q47. Given that listOfWords points to a List of words, which of the following code snippets will create a list of two letter words?

You had to select 3 option(s)

Q48. Given:

public class Book {
private String title;
private String genre;
public Book(String title, String genre){
this.title = title; this.genre = genre;
}
//accessors not shown
}

and the following code:

List books = Arrays.asList(
new Book("Gone with the wind", "Fiction"),
new Book("Bourne Ultimatum", "Thriller"),
new Book("The Client", "Thriller")
);

Reader r = b->{
System.out.println("Reading book "+b.getTitle());
};
books.forEach(x->r.read(x));

What would be a valid definition of Reader for the above code to compile and run without any error or exception?

You had to select 2 option(s)

Q49. 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.

You had to select 2 option(s)

Q50. Given:

public static void main(String[] args) {
String str = "10";
int iVal = 0;
Double dVal = 0.0;
try{
iVal = Integer.parseInt(str, 2); //1
if((dVal = Double.parseDouble(str)) == iVal){ //2
System.out.println("Equal");
}
}catch(NumberFormatException e){
System.out.println("Exception in parsing");
}
System.out.println(iVal+" "+dVal);

}

What is the result?

You had to select 1 option(s)

Q51. Identify the right declaration for 'box' for the following code.

import java.util.*;
class Dumper {
// declaration for box

public void dumpStuff(){
for(List l : box.values()){
System.out.println(l);
}
}
}

You had to select 2 option(s)

Q52. What will the following program print when run?

// Filename: TestClass.java
public class TestClass{
public static void main(String args[] ){ A b = new B("good bye"); }
}
class A{
A() { this("hello", " world"); }
A(String s) { System.out.println(s); }
A(String s1, String s2){ this(s1 + s2); }
}
class B extends A{
B(){ super("good bye"); };
B(String s){ super(s, " world"); }
B(String s1, String s2){ this(s1 + s2 + " ! "); }
}

You had to select 1 option(s)

Q53. Given that daylight Savings Time starts on March 13th, 2022 at 2 AM in US/Eastern time zone. (As a result, 2 AM becomes 3 AM. In other words, 1 minute after 1.59AM, the clock goes to 3.00 AM instead of 2 AM), what will the following code print?

LocalDateTime ld1 = LocalDateTime.of(2022, Month.MARCH, 13, 2, 0);
ZonedDateTime zd1 = ZonedDateTime.of(ld1, ZoneId.of("US/Eastern"));
LocalDateTime ld2 = LocalDateTime.of(2022, Month.MARCH, 13, 3, 0);
ZonedDateTime zd2 = ZonedDateTime.of(ld2, ZoneId.of("US/Eastern"));
long x = ChronoUnit.HOURS.between(zd1, zd2);
System.out.println(x);

You had to select 1 option(s)

Q54. Given that New York is 3 hours ahead of Los Angeles, what will the following code print?

LocalDateTime ldt = LocalDateTime.of(2022, 12, 02, 6, 0, 0);
ZonedDateTime nyZdt = ldt.atZone(nyZone);
ZonedDateTime laZdt = ldt.atZone(laZone);
Duration d = Duration.between(nyZdt, laZdt);
System.out.println(d);

You had to select 1 option(s)

Q55. What will be the output when the following code is compiled and run?

class Person implements Serializable{
String name;
Person(String name){
this.name = name;
System.out.print("Person ");
}
public String toString(){ return name; }
}

class Student extends Person{
String school;
public Student(String name, String school){
super(name);
this.school = school;
System.out.print("Student ");
}
public String toString(){
return super.toString()+" "+school;
}
}
public class SerialTest {
public static void main(String[] args) throws Exception {
Person p = new Student("Bob Dylan", "NYU");
try(
ObjectOutputStream oos = new ObjectOutputStream(
new FileOutputStream("c:\\temp\\student.ser"));

ObjectInputStream ois = new ObjectInputStream(
new FileInputStream("c:\\temp\\student.ser"));
){
oos.writeObject(p);
oos.flush();
System.out.println((Person)ois.readObject());
}
}
}

You had to select 1 option(s)