Java Test 6 - 2024

Q1. What will the following code print?

Map map1 = new HashMap();
map1.put("a", 1);
map1.put("b", 1);
map1.merge("b", 1, (i1, i2)->i1+i2);
map1.merge("c", 3, (i1, i2)->i1+i2);
System.out.println(map1);

You had to select 1 option(s)

Q2. Which of the given option when inserted in the code below will make the code print true?

List values = Arrays.asList("Alpha A", "Alpha B", "Alpha C");
//INSERT CODE HERE
System.out.println(flag);

You had to select 1 option(s)

Q3. When is the Object created at line //1 eligible for garbage collection?

public class TestClass{
public Object getObject(){
Object obj = new String("aaaaa"); //1
Object objArr[] = new Object[1]; //2
objArr[0] = obj; //3
obj = null; //4
objArr[0] = null;//5
return obj; //6
}
}

You had to select 1 option(s)

Q4. Given the following code:

interface Device {
public abstract void switchOn();
}

abstract class Router /* LOCATION 1 */ {
/* LOCATION 2 */
public void switchOn(){ }

public abstract void reset();
}

class MimoRouter extends Router implements Device{
/* LOCATION 3 */
}

Which code, when inserted at one or more marked locations, would allow classes Router and MimoRouter to compile?
(Consider each option as independent of other options.)

You had to select 2 option(s)

Q5. Consider the following code:

class MyClass { }
public class TestClass{
MyClass getMyClassObject(){
MyClass mc = new MyClass(); //1
return mc; //2
}
public static void main(String[] args){
TestClass tc = new TestClass(); //3
MyClass x = tc.getMyClassObject(); //4
System.out.println("got myclass object"); //5
x = new MyClass(); //6
System.out.println("done"); //7
}
}

After what line the MyClass object created at line 1 will be eligible for garbage collection?

You had to select 1 option(s)

Q6. Consider the following class hierarchy

class A{
public void m1() { }
}
class B extends A{
public void m1() { }
}
class C extends B{
public void m1(){
/* //1
... lot of code.
*/
}
}

Which of the following options are correct?

You had to select 2 option(s)

Q7. Given the following code that appears inside a method:

var values = new ArrayList();
//INSERT CODE HERE

What can be inserted at the given location without causing any compilation error?

You had to select 2 option(s)

Q8. Your application is packaged in myapp.jar and depends on a jar named datalayer.jar, which in turn depends on mysql-connector-java-8.0.11.jar. The following packages exist in these jars:

myapp.jar: com.abc.myapp
datalayer.jar: com.abc.datalayer
mysql-connector-java-8.0.11.jar: com.mysql.jdbc


You have decided to modularize your application even though datalayer and mysql libraries are still not modularlized. Which of the following would be a valid module-info for your app?

You had to select 1 option(s)

Q9. Given:

enum Card
{
HEART, CLUB, SPADE, DIAMOND;

public boolean isRed(){
return switch(this){
case HEART, DIAMOND -> true;
default -> false;
};
}
}


What will the following code print?


Arrays.stream(Card.values()).dropWhile(c->c.isRed());
switch(Card.valueOf("HEART")){
case HEART -> System.out.println("heart");
case CLUB -> System.out.println("club");
case SPADE -> System.out.println("spade");
case DIAMOND -> System.out.println("diamond");
default -> System.out.println("unknown");
}

You had to select 1 option(s)

Q10. Consider the following classes...

class Point { int x, y; }
class ColoredPoint extends Point { int color; }
class Test
{
static void test(ColoredPoint p, Point q)
{
System.out.println("(ColoredPoint, Point)");
}
static void test(Point p, ColoredPoint q)
{
System.out.println("(Point, ColoredPoint)");
}
public static void main(String[] args)
{
ColoredPoint cp = new ColoredPoint();
test(cp, cp);
}
}

The above code will print (ColoredPoint, Point) when compiled and run.

You had to select 1 option(s)

Q11. Consider the following class...

class TestClass{
void probe(Object x) { System.out.println("In Object"); } //3

void probe(Number x) { System.out.println("In Number"); } //2

void probe(Integer x) { System.out.println("In Integer"); } //2

void probe(Long x) { System.out.println("In Long"); } //4

public static void main(String[] args){
double a = 10;
new TestClass().probe(a);
}
}

What will be printed?

You had to select 1 option(s)

Q12. Which of the following code fragments will successfully initialize a two-dimensional array of chars named cA with a size such that cA[2][3] refers to a valid element?

1.
char[][] cA = { { 'a', 'b', 'c' }, { 'a', 'b', 'c' } };
2.
char cA[][] = new char[3][];
for (int i=0; i<cA.length; i++) cA[i] = new char[4];
3.
char cA[][] = { new char[ ]{ 'a', 'b', 'c' } , new char[ ]{ 'a', 'b', 'c' } };
4
char cA[3][2] = new char[][] { { 'a', 'b', 'c' }, { 'a', 'b', 'c' } };
5.
char[][] cA = { "1234", "1234", "1234" };

6.
var cA[][] = new char[3][];
for (var i=0; i<cA.length; i++) cA[i] = new char[4];

You had to select 1 option(s)

Q13. Identify correct constructs.

You had to select 1 option(s)

Q14. Given:

class Base{
public List transform(Set list){
//valid code
};
}

class Derived extends Base{
*INSERT CODE HERE*
//valid code
}
}

What can be inserted in the above code?

You had to select 2 option(s)

Q15. Given:

interface Runner {
public void run();
}

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

You had to select 2 option(s)

Q16. Assuming that the local time when the following code is executed is 9.30 AM, what will it print?

LocalTime now = LocalTime.now();
LocalTime gameStart = LocalTime.of(10, 15);
long timeConsumed = 0;
long timeToStart = 0;
if(now.isAfter(gameStart)){
timeConsumed = gameStart.until(now, ChronoUnit.HOURS);
}else{
timeToStart = now.until(gameStart, ChronoUnit.HOURS);
}
System.out.println(timeToStart + " " + timeConsumed);

You had to select 1 option(s)

Q17. What will the following code print when compiled and run?

import java.io.Serializable;
class Booby{
int i; public Booby(){ i = 10; System.out.print("Booby"); }
}
class Dooby extends Booby implements Serializable {
int j; public Dooby(){ j = 20; System.out.print("Dooby"); }
}
class Tooby extends Dooby{
int k; public Tooby(){ k = 30; System.out.print("Tooby"); }
}
public class TestClass {
public static void main(String[] args) throws Exception{

var t = new Tooby();
t.i = 100;
var oos = new ObjectOutputStream(new FileOutputStream("c:\\temp\\test.ser"));
oos.writeObject(t); oos.close();

var ois = new ObjectInputStream(new FileInputStream("c:\\temp\\test.ser"));
t = (Tooby) ois.readObject();ois.close();

System.out.println(t.i+" "+t.j+" "+t.k);
}
}

You had to select 1 option(s)

Q18. What will the following method return if called with an argument of 7?

public int transformNumber(int n){
var radix = 2;
var output = 0;
output += radix*n;
radix = output/radix;
if(output<14){
return output;
}
else{
output = output*radix/2;
return output;
}
else {
return output/2;
}
}

You had to select 1 option(s)

Q19. Consider the following code:

import java.util.*;
public class TestClass
{
static String[] sa = { "charlie", "bob", "andy", "dave" };
public static void main(String[] args)
{
// 1 insert code here.
}
}

Which of the given options (independent of each other or together) must be inserted at //1 so that it will print 2?

You had to select 2 option(s)

Q20. Given:

class Booby{
}
class Dooby extends Booby{
}
class Tooby extends Dooby{
}

and the following declarations:

var bL = new ArrayList();
var tL = new ArrayList();

List bV = //code for initialization
List dV = //code for initialization

Which of the following statements are valid?

You had to select 4 option(s)

Q21. What will the following code snippet print?

Object t = Integer.valueOf(107);
int k = (Integer) t.intValue()/9;
System.out.println(k);

You had to select 1 option(s)

Q22. In which sequence will the characters a, b, and, c be printed by the following program?

import java.util.* ;
public class ListTest{
public static void main(String args[]){
List s1 = new ArrayList( );
s1.add("a");
s1.add("b");
s1.add(1, "c");
List s2 = new ArrayList( s1.subList(1, 1) );
s1.addAll(s2);
System.out.println(s1);
}
}

You had to select 1 option(s)

Q23. Given:

1. Java source file location: src/moduleA/a/A.java
2. Expected class file location: out/moduleA/a/A.class

Which of the following commands will generate A.class in the expected directory?
(Assume that all directory paths are relative to the current directory.)

You had to select 1 option(s)

Q24. Consider the following interface definition:

interface Bozo{
int type = 0;
public void jump();
}


Now consider the following class:

public class Type1Bozo implements Bozo{
public Type1Bozo(){
type = 1;
}

public void jump(){
System.out.println("jumping..."+type);
}

public static void main(String[] args){
Bozo b = new Type1Bozo();
b.jump();
}
}

What will the program print when compiled and run?

You had to select 1 option(s)

Q25. How will you initialize a SimpleDateFormat object so that the following code will print the full text time zone of the given date?

System.out.println(sdf.format(new Date()));

Note: Although this SimpleDateFormat is not mentioned explicitly in the exam objectives, it is used a lot in legacy code. Read about this class if you have time. Otherwise, leave it.

You had to select 1 option(s)

Q26. What will the following program print?

public class TestClass{
public static void main(String[] args){
int x = 1;
int y = 0;
if( x/y ) System.out.println("Good");
else System.out.println("Bad");
}
}

You had to select 1 option(s)

Q27. What will be the output of the following class:

public class TestClass{
public void testRefs(String str, StringBuilder sb){
str = str + sb.toString();
sb.append(str);
str = null;
sb = null;
}
public static void main(String[] args){
String s = "aaa";
StringBuilder sb = new StringBuilder("bbb");
new TestClass().testRefs(s, sb);
System.out.println("s="+s+" sb="+sb);
}
}

You had to select 1 option(s)

Q28. What will the code shown below print when run?

class Wrapper{
int w = 10;
}

public class TestClass{

static Wrapper changeWrapper(Wrapper w){
w = new Wrapper();
w.w += 9;
return w;
}


public static void main(String[] args){
var w = new Wrapper();
w.w = 20;
changeWrapper(w);
w.w += 30;
System.out.println(w.w);
w = changeWrapper(w);
System.out.println(w.w);
}
}

You had to select 2 option(s)

Q29. Consider the following class...

class TestClass{
int x;
public static void main(String[] args){
// lot of code.
}
}

You had to select 1 option(s)

Q30. What will the following code snippet print:

Float f = null;
try{
f = Float.valueOf("12.3");
String s = f.toString();
int i = Integer.parseInt(s);
System.out.println(""+i);
}
catch(Exception e){
System.out.println("trouble : "+f);
}

You had to select 1 option(s)

Q31. Consider the following code:

class A{
A() { print(); }
void print() { System.out.print("A "); }
}
class B extends A{
int i = 4;
public static void main(String[] args){
A a = new B();
a.print();
}
void print() { System.out.print(i+" "); }
}

What will be the output when class B is run ?

You had to select 1 option(s)

Q32. What will be the result of attempting to compile the following program?

public class TestClass{
long l1;
public void TestClass(long pLong) { l1 = pLong ; } //(1)
public static void main(String args[]){
TestClass a, b ;
a = new TestClass(); //(2)
b = new TestClass(5); //(3)
}
}

You had to select 1 option(s)

Q33. Given:

public class Square {
private double side = 0; // LINE 2

public static void main(String[] args) { // LINE 4
Square sq = new Square(); // LINE 5
side = 10; // LINE 6
}
}

What can be done to make this code compile and run?

You had to select 1 option(s)

Q34. Given:

class Person{
String name;
String dob;
public Person(String name, String dob){
this.name = name; this.dob = dob;
}
}
class MySorter {
public int compare(Person p1, Person p2){
return p1.dob.compareTo(p2.dob);
}
}
public class SortTest {
public static int diff(Person p1, Person p2){
return p1.dob.compareTo(p2.dob);
}

public static int diff(Date d1, Date d2){
return d1.compareTo(d2);
}
public static void main(String[] args) {
ArrayList al = new ArrayList();
al.add(new Person("Paul", "01012000"));
al.add(new Person("Peter", "01011990"));
al.add(new Person("Patrick", "01012002"));

INSERT CODE HERE
}
}

and the following lines of code:
I java.util.Collections.sort(al, (p1, p2)->p1.dob.compareTo(p2.dob));

II java.util.Collections.sort(al, SortTest::diff);

III java.util.Collections.sort(al, new MySorter()::compare);

IV java.util.Arrays.sort(al, SortTest::diff);

How many of the above lines can be inserted into the given code, independent of each other, to sort the list referred to by al?

You had to select 1 option(s)

Q35. Which of the given options if put at //1 will compile without any error?

public class TestClass
{
public class A
{
}
public static class B
{
}
public void useClasses()
{
//1
}
}

You had to select 1 option(s)

Q36. You are creating an enthu.questionbank module that depends on enthu.internal.db and enthu.external.feeds modules. Which of the following files correctly defines this module?

You had to select 1 option(s)

Q37. How can you declare 'i' so that it is not visible outside the package test.

package test;
public class Test{
XXX int i;
/* irrelevant code */
}

You had to select 2 option(s)

Q38. Given a Course class with appropriate constructor and methods and the following code:

List s1 = //create a list with a few Course objects
String testCategory = "Java";
Integer comparisonCode = 0;
long l = s1.stream()
.peek(new Consumer(){
public void accept(Course c){
c.printPassPercent();
}})
.map(c -> testCategory.compareToIgnoreCase(c.getCategory()))
.filter(a->comparisonCode.equals(a))
.count();
System.out.println(l);

Which of the method arguments can be changed to use method references?

You had to select 2 option(s)

Q39. Given:

var data = new ArrayList();
data.add("A");
data.add(100); //1
data.add("C");
data.set(0, 200); //2
data.remove(2); //3
data.set(2, 101L);//4
System.out.println(data);

What will be the output?

You had to select 1 option(s)

Q40. Which of the following expressions can be used to implement a Function ?

You had to select 3 option(s)

Q41. Assuming that a file named "a.java" exists in c:\pathtest\ as well as in c:\pathtest\dir2, what will happen when the following code is compiled and run?

//imports not shown
public class MoveTest {

public static void main(String[] args) throws IOException {
Path p1 = Paths.get("c:\\pathtest\\a.java");
Path p2 = Paths.get("c:\\pathtest\\dir2\\a.java");
Files.move(p1, p2, StandardCopyOption.ATOMIC_MOVE);
Files.delete(p1);
System.out.println(p1.toFile().exists()+" "+
p2.toFile().exists());
}
}

You had to select 1 option(s)

Q42. Given:

record Student(int id, String name) {
}

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

You had to select 3 option(s)

Q43. Given:

public class Device implements AutoCloseable{
boolean open = false;
public Device(){
open = true;
}

public String read() throws IOException{
throw new IOException("Can't read!");
}

public boolean isOpened(){
return open;
}

public void close(){
open = false;
System.out.println("Device closed");
}

public static void main(String[] args) {
Device d1 = new Device();
try(d1;
Device d2 = new Device();
Device d3 = new Device()){
d2.read();
}catch(Exception e){
System.out.println("Got Exception "+e.getMessage());
}
}
}

What is the status of Device objects at the end of the try/catch blocks?

You had to select 1 option(s)

Q44. What will be the output when the following program is run?

public class TestClass{
public static void main(String args[]){
int i;
int j;
for (i = 0, j = 0; j < i; ++j, i++){
System.out.println(i + " " + j);
}
System.out.println(i + " " + j);
}
}

You had to select 1 option(s)

Q45. 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?

You had to select 1 option(s)

Q46. What can be inserted in the code below so that it will print 1 2 3?

class MyProcessor{
Integer value;
public MyProcessor(Integer value){
this.value = value;
}
public void process(){
System.out.println(value+" ");
}
}
public class TestClass {

public static void main(String[] args) {
List ls = Arrays.asList(1, 2, 3);

INSERT CODE HERE
}
}

You had to select 1 option(s)

Q47. Given:

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

and

Stream sm = Stream.of( new Movie("a1", "a"),
new Movie("a2", "a"),
new Movie("b1", "b"), new Movie("c1", null));


Which of the following code fragments will get you the map of all the genres and the number of movies belonging to each genre?

You had to select 1 option(s)

Q48. Consider the following code:

import java.util.concurrent.*;

public class ThreadPoolTest {
public static void main(String[] args) {
Runnable r = ()-> System.out.println("In Runnable");
Callable c = ()-> { System.out.println("In Callable"); return 0; };
var es = Executors.newCachedThreadPool();

//INSERT CODE HERE

es.shutdown();

}

}

What can be inserted in the above code so that both - Runnable r and Callable c - will be executed?

You had to select 1 option(s)

Q49. What will the following code print?

List ls = Arrays.asList(1, 2, 3);
Function func = a->a*a; //1
ls.stream().map(func).peek(System.out::print); //2

You had to select 1 option(s)

Q50. Consider the following class and interface definitions (in separate files):

public class Sample implements IInt{
public static void main(String[] args){
Sample s = new Sample(); //1
int j = s.thevalue; //2
int k = IInt.thevalue; //3
int l = thevalue; //4
}
}
public interface IInt{
int thevalue = 0;
}


What will happen when the above code is compiled and run?

You had to select 1 option(s)

Q51. Which line(s) of code in the following program will cause compilation errors?

public class TestClass{
var value = 0; //1
public static void main(var args[]) //2
{
var secondArg = Integer.parseInt(args[2]); //3
if( true == 2 > 10 ) //4
{
value = -10;
}
else{
value = secondArg;
}
for( ; value>0; value--) System.out.println("A"); //5
}
}

You had to select 3 option(s)

Q52. What will the following code print when run?

import java.util.*;
import java.text.*;

public class TestClass
{
public static void main(String[] args)
{
double amount = 123456.789;
Locale fr = new Locale("fr", "FR");
NumberFormat formatter = NumberFormat.getInstance(fr);
String s = formatter.format(amount) ;
formatter = NumberFormat.getInstance();
Number amount2 = formatter.parse(s);
System.out.println( amount + " " + amount2 );
}
}

You had to select 1 option(s)

Q53. Assuming that getValue returns an int, which of the following options can be used in the code below:

int x = getValue();
String s = INSERT CODE HERE

You had to select 2 option(s)

Q54. What will the following code print ?

class Test{
public static void main(String[] args){
int k = 1;
int[] a = { 1 };
k += (k = 4) * (k + 2);
a[0] += (a[0] = 4) * (a[0] + 2);
System.out.println( k + " , " + a[0]);
}
}

You had to select 1 option(s)

Q55. Which of the following method(s) of java.util.stream.Stream interface is/are used for reduction?

You had to select 2 option(s)