Advanced Java Practice Test: 2024 Technical Interview Prep

Q1. Which exact exception class will the following class throw when compiled and run?

class Test{
public static void main(String[] args) throws Exception{
int[] a = null;
int i = a [ m1() ];
}
public static int m1() throws Exception{
throw new Exception("Some Exception");
}
}

You had to select 1 option(s)

Q2. What will the following code print when run?

public class TestClass {

public void switchString(String input){
switch(input){
case "a" : System.out.println( "apple" );
case "b" : System.out.println( "bat" );
break;
case "c" : System.out.println( "cat" );
default : System.out.println( "none" );
}
}

public static void main(String[] args) throws Exception {
var tc = new TestClass();
tc.switchString("c");
}
}

You had to select 1 option(s)

Q3. Given the following module-info:

module book{
requires org.pdf;
uses org.pdf.Print;
}

Which of the following statements are correct?

You had to select 1 option(s)

Q4. What will be printed when the following code is compiled and run?

package trywithresources;

import java.io.IOException;

public class Device{
String header = null;
public void open(){
header = "OPENED";
System.out.println("Device Opened");
}
public String read() throws IOException{
throw new IOException("Unknown");
}

public void writeHeader(String str) throws IOException{
System.out.println("Writing : "+str);
header = str;
}
public void close(){
header = null;
System.out.println("Device closed");
}

public static void testDevice(){
try(Device d = new Device()){
d.open();
d.read();
d.writeHeader("TEST");
d.close();
}catch(IOException e){
System.out.println("Got Exception");
}
}
public static void main(String[] args) {
Device.testDevice();
}

}

You had to select 1 option(s)

Q5. What will the following program print?

class Test{
public static void main(String args[]){
var c = 0;
var flag = true;
for(var i = 0; i < 3; i++){
while(flag){
c++;
if(i>c || c>5) flag = false;
}
}
System.out.println(c);
}
}

You had to select 1 option(s)

Q6. Given:

List dList = Arrays.asList(10.0, 12.0);
DoubleFunction df = x->x+10;
dList.stream().forEach(df);
dList.stream().forEach(d->System.out.println(d));

What will it print when compiled and run?

You had to select 1 option(s)

Q7. Given:

package strings;
public class StringFromChar {

public static void main(String[] args) {
String myStr = "good";
char[] myCharArr = {'g', 'o', 'o', 'd' };

String newStr = null;
for(char ch : myCharArr){
newStr = newStr + ch;
}

System.out.println((newStr == myStr)+ " " + (newStr.equals(myStr)));

}
}

What will it print when compiled and run?

You had to select 1 option(s)

Q8. Consider the following class written by a novice programmer.

class Elliptical{
public int radiusA, radiusB;
public int sum = 100;

public void setRadius(int r){
if(r>99) throw new IllegalArgumentException();
radiusA = r;
radiusB = sum - radiusA;

}
}
After some time, the requirements changed and the programmer now wants to make sure that radiusB is always (200 - radiusA) instead of (100 - radiusA) without breaking existing code that other people have written. Which of the following will accomplish his goal?

You had to select 1 option(s)

Q9. A programmer is using the following class for wrapping objects and passing it around to multiple threads. Which of the given statements regarding this class are correct?

public class DataObjectWrapper
{
private final Object obj;

public DataObjectWrapper(Object pObj){ obj = pObj; }

public Object getObject() { return obj; }
}

You had to select 1 option(s)

Q10. What will the following program print?

public class TestClass{
public static void main(String[] args){
unsigned byte b = 0;
b--;
System.out.println(b);
}
}

You had to select 1 option(s)

Q11. Given:

interface Account{
public default String getId(){
return "0000";
}
}

interface PremiumAccount extends Account{
//INSERT CODE HERE
}

Which of the following options can be inserted in PremiumAccount independent of each other?
Answered Incorrectly

You had to select 2 option(s)

Q12. What will the following code fragment print when compiled and run?

Statement stmt = null;
Connection c = DriverManager.getConnection("jdbc:derby://localhost:1527/sample",
"app", "app");
try(stmt = c.createStatement();)
{

ResultSet rs = stmt.executeQuery("select * from STUDENT");
while(rs.next()){
System.out.println(rs.getString(0));
}

}
catch(SQLException e){
System.out.println("Exception ");
}

(Assume that the method in which this code appears has appropriate throws clause.)

You had to select 1 option(s)

Q13. What can you do to make the following code compile?

public class TestClass {
public static void main(String[] args) {
int[] values = { 10, 20, 30 };
for( /* put code here */ ){
}
}
}

You had to select 2 option(s)

Q14. Given:

List lon = List.of(1, 2, 3, 4, 5, 6, 7);

Which of the following may return a different value every time it is executed?

You had to select 1 option(s)

Q15. Consider the following code:

//Assume appropriate imports
public class FileCopier {

public static void copy(String records1, String records2) throws IOException {
try (
InputStream is = new FileInputStream(records1);
OutputStream os = new FileOutputStream(records2);) {
var buffer = new byte[1024];
var bytesRead = 0;
while ((bytesRead = is.read(buffer)) != -1) {
os.write(buffer, 0, bytesRead);
}

} catch (FileNotFoundException | java.io.InvalidClassException e) {
e.printStackTrace();
}
}

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

Given that test1.txt exists but test2.txt does not exist, what will happen when the above program is compiled and run?

You had to select 1 option(s)

Q16. What will be the result of attempting to compile and run the following program?

public class TestClass{
public static void main(String args[ ] ){
StringBuilder sb = new StringBuilder("12345678");
sb.setLength(5);
sb.setLength(10);
System.out.println(sb.length());
}
}

You had to select 1 option(s)

Q17. What will be the result of attempting to compile and run the following class?

public class TestClass{
public static void main(String args[ ] ){
int i = 1;
int[] iArr = {1};
incr(i) ;
incr(iArr) ;
System.out.println( "i = " + i + " iArr[0] = " + iArr [ 0 ] ) ;
}
public static void incr(int n ) { n++ ; }
public static void incr(int[ ] n ) { n [ 0 ]++ ; }
}

You had to select 1 option(s)

Q18. Identify the correct statements regarding DateFormat and NumberFormat classes.

You had to select 1 option(s)

Q19. Consider the following code:

var s = "hello";
byte i = 100;
var fos = new FileOutputStream("c:\\temp\\data.bin");
var dos = new DataOutputStream(fos);
//WRITE s to file
//WRITE i to file
dos.flush(); dos.close(); fos.close();

var dis = new DataInputStream(new FileInputStream("c:\\temp\\data.bin"));
//READ s from file
//READ i from file


Which methods should be used to write and read s and i to/from the data.bin file?

You had to select 1 option(s)

Q20. What will the following code print?

AtomicInteger ai = new AtomicInteger();
Stream stream = Stream.of(
"old", "king", "cole", "was", "a", "merry", "old", "soul")
.parallel();
stream.filter( e->{
ai.incrementAndGet();
return e.contains("o");
}).allMatch(x->x.indexOf("o")>0);

System.out.println("AI = "+ai);

You had to select 1 option(s)

Q21. Which of the following are correct about "encapsulation"?

You had to select 2 option(s)

Q22. Given:

public class Book{
private int id;
private String title;
//constructors and accessors not shown
}

Assuming that book is a reference to a valid Book object, which of the following code fragments correctly prints the details of the Book?

You had to select 1 option(s)

Q23. Given:

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

Which of the following options will fail to compile?

You had to select 1 option(s)

Q24. Given: Daylight Savings Time ends on Nov 6 at 2 AM in US/Eastern time zone. As a result, 2 AM becomes 1 AM. In other words, one minute after 1.59 AM, the clock shows 1 AM instead of 2 AM.

What will the following code print ?

LocalDateTime ld = LocalDateTime.of(2022, Month.NOVEMBER, 5, 10, 0);

ZonedDateTime date = ZonedDateTime.of(ld, ZoneId.of("US/Eastern"));
date = date.plus(Duration.ofDays(1));
System.out.println(date);

date = ZonedDateTime.of(ld, ZoneId.of("US/Eastern"));
date = date.plus(Period.ofDays(1));
System.out.println(date);

You had to select 1 option(s)

Q25. Consider the following code appearing in Eagle.java

class Bird {
private Bird(){ }
}
class Eagle extends Bird {
public String name;
public Eagle(String name){
this.name = name;
}

public static void main(String[] args) {
System.out.println(new Eagle("Bald Eagle").name);
}
}

What can be done to make this code compile?

You had to select 1 option(s)

Q26. Consider the following classes in one file named A.java...

abstract class A{
protected int m1(){ return 0; }
}
class B extends A{
@Override
int m1(){ return 1; }
}

Which of the following statements are correct.

You had to select 1 option(s)

Q27. Identify correct statement about the following code -

class X{
int val = 10;
}

class Y extends X{
Y val = null; //1
}

public class TestClass extends X{

public static void main(String[] args){
Y y = new Y();
int k = (X) y.val ; //2
System.out.println(k);

}
}

You had to select 1 option(s)

Q28. MOVE What is the result of compiling and running the following code ?

public class TestClass{
static int si = 10;
public static void main (String args[]){
new TestClass();
}
public TestClass(){
System.out.println(this);
}
public String toString(){
return "TestClass.si = "+this.si;
}
}

You had to select 1 option(s)

Q29. Given:

import java.util.*;

class Student{
int marks;
}

public class TestClass {
static var getHighest(var students){
int highest = 0;
for(var student : students){
if(highest }
return highest;
}

public static void main(String[] args) {

var student = new Student();

var allStudents = new ArrayList();

allStudents.add(student);

var h = getHighest(allStudents);

System.out.println(h);
}

}

Identify correct statements about the above code.

You had to select 1 option(s)

Q30. What will the following code print?

import java.util.Optional;
public class NewClass {
public static Optional getGrade(int marks){
Optional grade = Optional.empty();
if(marks>50){
grade = Optional.of("PASS");
}
else {
grade.of("FAIL");
}
return grade;
}
public static void main(String[] args) {
Optional grade1 = getGrade(50);
Optional grade2 = getGrade(55);
System.out.println(grade1.orElse("UNKNOWN"));
if(grade2.isPresent()){
grade2.ifPresent(x->System.out.println(x));
}else{
System.out.println(grade2.orElse("Empty"));
}
}
}

You had to select 1 option(s)

Q31. Given:

class A{
public List getList(){
//valid code
};
}
class B extends A{
@Override
*INSERT CODE HERE*
//valid code
};
}

What can be inserted in the above code?

You had to select 1 option(s)

Q32. Consider the following code for the main() method:

public static void main(String[] args) throws Exception{
int i = 1, j = 10;
do {
if (i++ > --j) continue;
} while (i < 5);
System.out.println("i=" + i + " j=" + j);
}

What will be the output when the above code is executed?

You had to select 1 option(s)

Q33. Given:

class Base{
public Collection transform(Collection list)
{
return new ArrayList();
}

}

class Derived extends Base{
//public Collection transform(Collection list) {
return new HashSet(); }; //1

//public Collection transform(Collection list) {
return new HashSet();}; //2

//public List transform(Collection list) {
return new ArrayList(); }; //3

//public Collection transform(List list) {
return new HashSet(); }; //4

//public Collection transform(List list) {
return new HashSet(); };//5

//public Collection transform(Collection list) {
return new HashSet();}; //6
}


Identify correct statements about the methods defined in Derived assuming they are uncommented one at a time individually.
(Ignore the extra line breaks.)

You had to select 1 option(s)

Q34. Given:

public static void main(String[] args){
FileInputStream tempFis = null;
try(FileInputStream fis = new FileInputStream("c:\\temp\\test.text")){
System.out.println(fis);
tempFis = fis;
}
//line 1
}

Which of the following options can be inserted at //1 independent of each other to make the above code compile?

You had to select 2 option(s)

Q35. What will the following code print when compiled and run:

class Data {

int intVal = 0;
String strVal = "default";
public Data(int k){
this.intVal = k;
}

}

public class TestClass {
public static void main(String[] args) throws Exception {
Data d1 = new Data(10);
d1.strVal = "D1";
Data d2 = d1;
d2.intVal = 20;
System.out.println("d2 val = "+d2.strVal);
}
}

You had to select 1 option(s)

Q36. Which of the following statements are correct regarding the module system of Java.

You had to select 1 option(s)

Q37. Given:

class Base{
public ArrayList 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 1 option(s)

Q38. Following is a supposedly robust method to parse an input for a float :

public float parseFloat(String s){
float f = 0.0f;
try{
f = Float.valueOf(s).floatValue();
return f ;
}
catch(NumberFormatException nfe){
System.out.println("Invalid input " + s);
f = Float.NaN ;
return f;
}
finally { System.out.println("finally"); }
return f ;
}

Which of the following statements about the above method is/are true?

You had to select 1 option(s)

Q39. What will the following code print?

List s1 = new ArrayList( );
s1.add("a");
s1.add("b");
s1.add("c");
s1.add("a");
System.out.println(s1.remove("a")+" "+s1.remove("x"));

You had to select 1 option(s)

Q40. What will be the result of attempting to compile and run the following code?

You had to select 1 option(s)

Q41. Given the following definitions and reference declarations:

interface I1 { }
interface I2 { }
class C1 implements I1 { }
class C2 implements I2 { }
class C3 extends C1 implements I2 { }
C1 o1;
C2 o2;
C3 o3;

Which of these statements are legal?

You had to select 3 option(s)

Q42. Assuming the following enum declaration and a variable s of type Switch, identify potentially valid code fragments.

public enum Switch{ ON, OFF }

You had to select 3 option(s)

Q43. What will the following code print when compiled and run?

var strList1 = new ArrayList();
strList1.add("A");
var strList2 = Collections.unmodifiableList(strList1);
strList1.add(null);
System.out.println(strList1+" "+strList2);
strList2.add(null);
System.out.println(strList1+" "+strList2);

You had to select 2 option(s)

Q44. Which statements about the output of the following programs are true?

public class TestClass{
public static void main(String args[ ] ){
int i = 0 ;
boolean bool1 = true;
boolean bool2 = false;
boolean bool = false;
bool = (bool2 & method1("1")); //1
bool = (bool2 && method1("2")); //2
bool = (bool1 | method1("3")); //3
bool = (bool1 || method1("4")); //4
}
public static boolean method1(String str){
System.out.println(str);
return true;
}
}

You had to select 2 option(s)

Q45. What will the following code fragment print?

Path p1 = Paths.get("x\\y");
Path p2 = Paths.get("z");
Path p3 = p1.relativize(p2);
System.out.println(p3);

You had to select 1 option(s)

Q46. Given:

public int switchTest(byte x){
return switch(x){ //1
case 'b', 'c' -> 10; //2
case -2 -> 20; // 3
case 80, default -> 30; // 4
};
}

What is the result?

You had to select 1 option(s)

Q47. In the following code, after which statement (earliest), the object originally held in s, may be garbage collected ?

1. public class TestClass{
2. public static void main (String args[]){
3. Student s = new Student("Vaishali", "930012");
4. s.grade();
5. System.out.println(s.getName());
6. s = null;
7. s = new Student("Vaishali", "930012");
8. s.grade();
9. System.out.println(s.getName());
10 s = null;
}
}

public class Student{
private String name, rollNumber;

public Student(String name, String rollNumber) {
this.name = name;
this.rollNumber = rollNumber;
}

//valid setter and getter for name and rollNumber follow

public void grade() {
}

}

You had to select 1 option(s)

Q48. Which of the following methods are available in java.io.Console?

You had to select 5 option(s)

Q49. Which of the following statements regarding java.util.HashSet is correct?

You had to select 1 option(s)

Q50. You want to use a module built by another team in your company. The name of the module is abc.math.utils and the module is packaged as a jar file named mathutils.jar. The module contains a class named abc.utils.Main.

You want to run this class from the command line. Which of the following commands can be used?
(Assume that the jar file is located in the current directory.)

You had to select 1 option(s)

Q51. Consider that str is a local variable of class java.lang.String.

Which of the following lines of code may throw a NullPointerException in certain situations?

Or a tougher version of the question could be :
Which of the following lines of code are not an example of robust design ?

You had to select 3 option(s)

Q52. Which of the following are valid?

(Assume the method bodies are valid.)

You had to select 3 option(s)

Q53. What changes should be applied to the following class to update it to use generics without changing any functionality? Choose minimal changes that are necessary to take advantage of generics.

import java.util.*;
public class BookStore {
Map map = new HashMap(); //1

public BookStore(){
map.put(new Book("A111"), Integer.valueOf(10)); //2
}

public int getNumberOfCopies(Book b){ //3
Integer i = (Integer) map.get(b); //4
return i == null? 0:i.intValue(); //5
}
}

You had to select 2 option(s)

Q54. You are creating an acme.accounting module that depends on acme.math module and makes its com.acme.accounting package available to all other modules. Which of the following files correctly defines this module?

You had to select 1 option(s)

Q55. Given:

double daaa[][][] = new double[3][][];
var d = 100.0;
double[][] daa = new double[1][1];

Which of the following statements can be added to the above code, independent of each other, without causing compilation or runtime errors?

You had to select 3 option(s)