Java Technical Assessment: Test Your Programming Proficiency

Q1. Given that your module named foo.bar contains the following two source files: src/foo.bar/f/b/Baz1.java and src/foo.bar/f/c/Caz1.java.

Which of the following options can be used to compile this module?

(Assume that all directory paths are relative to the current directory.)

You had to select 1 option(s)

Q2. What will happen on running the following program?

public class DatabaseWrapper
{
static String url = "jdbc://derby://localhost:1527//mydb";
static DatabaseWrapper getDatabase()
{
System.out.println("Getting DB");
return null;
}
public static void main(String[ ] args)
{
System.out.println( getDatabase().url );
}
}

You had to select 1 option(s)

Q3. What can be inserted into the following code at //1 so that it will print "Oldboy"?

//imports not shown
class Movie{
static enum Genre {DRAMA, THRILLER, HORROR, ACTION };
private Genre genre;
private String name;
Movie(String name, Genre genre){
this.name = name; this.genre = genre;
}
//accessors not shown
}
public class FilteringStuff {
public static void main(String[] args) {
List movies = Arrays.asList(
new Movie("On the Waterfront", Movie.Genre.DRAMA),
new Movie("Psycho", Movie.Genre.THRILLER),
new Movie("Oldboy", Movie.Genre.THRILLER),
new Movie("Shining", Movie.Genre.HORROR)
);
Predicate horror = mov->mov.getGenre() == Movie.Genre.THRILLER;
Predicate name = mov->mov.getName().startsWith("O");
//1 INSERT CODE HERE
.forEach(mov->System.out.println(mov.getName()));
}

}

You had to select 1 option(s)

Q4. What will be the result of compiling and running the following code?

class Base{
public short getValue(){ return 1; } //1
}
class Base2 extends Base{
public byte getValue(){ return 2; } //2
}
public class TestClass{
public static void main(String[] args){
Base b = new Base2();
System.out.println(b.getValue()); //3
}
}

You had to select 1 option(s)

Q5. Given :

You had to select 1 option(s)

Q6. Given:

public class TestClass
{
public static void main(String[] args) throws IOException {
final Reader reader = new FileReader("aaa.a"); //1
try(reader){
reader.read(); //2
}finally{
reader.read(); //3
}
reader.read(); //4
}
}

Assuming that the fle named aaa.a does not exist, what will be the outcome?

You had to select 1 option(s)

Q7. Which of the following statements will evaluate to true?

You had to select 1 option(s)

Q8. What will be the result of attempting to compile and run the following program?

class TestClass{
public static void main(String args[]){
var i = 0;
for (i=1 ; i<5 ; i++) continue; //(1)
for (i=0 ; ; i++) break; //(2)
for ( ; i<5?false:true ; ); //(3)
}
}

You had to select 1 option(s)

Q9. Given:

record Student(int id, String... subjects){
int rank;
public int getRank(){
return rank;
}
}


public class TestClass{

public static void main(String[] args) {
Student s = new Student(123, new String[]{"math", "science"});
System.out.println(s);
}
}


Which change(s) will enable the code to compile?

You had to select 1 option(s)

Q10. Given:

DoubleStream ds = DoubleStream.of(1.0, 2.0, 3.0);
//INSERT CODE HERE
ds.map(doubleF.apply(5.0)).forEach(System.out::println);

Which of the following statements can be inserted in the above code?

You had to select 1 option(s)

Q11. What will be the output of the following code snippet?

int a = 1;
int[] ia = new int[10];
int b = ia[a];
int c = b + a;
System.out.println(b = c);

You had to select 1 option(s)

Q12. A java source file contains the following code:

interface I {
int getI(int a, int b);
}

interface J{
int getJ(int a, int b, int c);
}

abstract class MyIJ implements J , I { }

class MyI{
int getI(int x, int y){ return x+y; }
}

interface K extends J{
int getJ(int a, int b, int c, int d);
}

Identify the correct statements:

You had to select 1 option(s)

Q13. What would be the result of attempting to compile and run the following program?

class TestClass{
static TestClass ref;
String[] arguments;
public static void main(String args[]){
ref = new TestClass();
ref.func(args);
}
public void func(String[] args){
ref.arguments = args;
}
}

You had to select 1 option(s)

Q14. What will the following program print?

class Test{
public static void main(String args[]){
int i=0, j=0;
X1: for(i = 0; i < 3; i++){
X2: for(j = 3; j > 0; j--){
if(i < j) continue X1;
else break X2;
}
}
System.out.println(i+" "+j);
}
}

You had to select 1 option(s)

Q15. What will the following code print when run?

public class TestClass {
public static void main(String[] args) throws Exception {
var sa = new String[]{"a", "b", "c"};
for(String s : sa){
if("b".equals(s)) continue;
System.out.println(s);
if("b".equals(s)) break;
System.out.println(s+" again");
}
}
}

You had to select 1 option(s)

Q16. What will be the output of the following program?

class Test
{
static int i1, i2, i3;
public static void main(String[] args)
{
try
{
test(i1 = 1, oops(i2=2), i3 = 3);
} catch (Exception e)
{
System.out.println(i1+" "+i2+" "+i3);
}
}
static int oops(int i) throws Exception
{
throw new Exception("oops");
}
static int test(int a, int b, int c) {
return a + b + c;
}
}

You had to select 1 option(s)

Q17. Given the following declarations, identify which statements will return true:

Integer i1 = 1;
Integer i2 = new Integer(1);
int i3 = 1;
Byte b1 = 1;
Long g1 = 1L;
Double d = 1.0;

You had to select 2 option(s)

Q18. You have a file named customers.dat in c:\company\records directory. You want to copy all the lines in this file to another file named clients.dat in the same directory and you have the following code to do it:

public static void writeData() {
Path p1 = Paths.get("c:\\company\\records\\customers.dat");

//LINE 20 - INSERT CODE HERE

try (
var br = new BufferedReader(new FileReader(p1.toFile()));
var bw = new BufferedWriter(new FileWriter(p2.toFile()))) {
String line = null;
while ((line = br.readLine()) != null) {

bw.write(line);
bw.newLine();
}
}catch(Exception e){
e.printStackTrace();
}
}

Which of the following options can be inserted independent of each other at //LINE 20 to make it work?

Assume that the current directory for the program when it runs is c:\code.

You had to select 2 option(s)

Q19. What will the following code print when run?

public class TestClass {
public static void m1() throws Exception{
throw new Exception("Exception from m1");
}
public static void m2() throws Exception{
try{
m1();
}catch(Exception e){
//Can't do much about this exception so rethrow it
throw e;
}finally{
throw new RuntimeException("Exception from finally");
}

}

public static void main(String[] args) {
try{
m2();
}catch(Exception e){
Throwable[] ta = e.getSuppressed();
for(Throwable t : ta) {
System.out.println(t.getMessage());
}
}
}
}

You had to select 1 option(s)

Q20. Consider following classes:

//In File Other.java
package other;
public class Other { public static String hello = "Hello"; }

//In File Test.java
package testPackage;
import other.*;
class Test{
public static void main(String[] args){
String hello = "Hello", lo = "lo";
System.out.print((testPackage.Other.hello == hello) + " "); //line 1
System.out.print((other.Other.hello == hello) + " "); //line 2
System.out.print((hello == ("Hel"+"lo")) + " "); //line 3
System.out.print((hello == ("Hel"+lo)) + " "); //line 4
System.out.println(hello == ("Hel"+lo).intern()); //line 5
}
}
class Other { static String hello = "Hello"; }

What will be the output of running class Test?

You had to select 1 option(s)

Q21. Given:

Instant now = Instant.now();
Instant now2 = //INSERT CODE HERE
System.out.println(now2);

Which of the following options can be inserted in the above code without causing any compilation or runtime errors?

You had to select 1 option(s)

Q22. Consider the code shown below:

public class TestClass{
public static int switchTest(int k){
var j = 1;
switch(k){
case 1: j++;
case 2: j++;
case 3: j++;
case 4: j++;
case 5: j++;
default : j++;
}
return j + k;
}
public static void main(String[] args){
System.out.println( switchTest(4) );
}
}

What will it print when compiled and run?

You had to select 1 option(s)

Q23. What will the following class print ?

class Test{
public static void main(String[] args){
int[][] a = { { 00, 01 }, { 10, 11 } };
int i = 99;
try {
a[val()][i = 1]++;
} catch (Exception e) {
System.out.println( i+", "+a[1][1]);
}
}
static int val() throws Exception {
throw new Exception("unimplemented");
}
}

You had to select 1 option(s)

Q24. Given:

class Course{
private String id;
private String name;

public Course(String id, String name){
this.id = id; this.name = name;
}
//accessors not shows
}

What will the following code print?

List cList = Arrays.asList(
new Course("803", "OCAJP 7"),
new Course("808", "OCAJP 8"),
new Course("809", "OCPJP 8")
);

cList.stream().filter(c->c.getName().indexOf("8")>-1)
.map(c->c.getId())
.collect(Collectors.joining("1Z0-"));
cList.stream().forEach(c->System.out.println(c.getId()));

You had to select 1 option(s)

Q25. Given:

class StaticTest{

void m1(){
StaticTest.m2(); // 1
m4(); // 2
StaticTest.m3(); // 3
}

static void m2(){ } // 4

void m3(){
m1(); // 5
m2(); // 6
StaticTest.m1(); // 7
}

static void m4(){ }
}

Which of the lines will fail to compile?

You had to select 2 option(s)

Q26. What will the following code print when compiled and run?

List list1 = List.of("A", "B");
List list2 = List.copyOf(list1);
list1.add("C"); //1
list2.add("D"); //2
System.out.println(list1+" "+list2);

You had to select 1 option(s)

Q27. Given:

public class TestClass {
static int val = 10;
public static int reduce(int val){
class Inner{
public int reduce(int mval){
return mval-val--;
}
}
val--;
return new Inner().reduce(val);
}

public static void main(String[] args) {
reduce(5);
System.out.println(val);
}
}

You had to select 1 option(s)

Q28. Given:

import java.util.*;
class Student{ }

public class TestClass {

var students = new ArrayList(); //1

public static void main(String[] args) {

var student = new Student(); //2

var allStudents = new ArrayList(); //3

allStudents.add(student); //4

for(var s : allStudents){ //5
System.out.println(s);
}
Student s2 = allStudents.get(0); //6

var var = "what?"; //7
}

}

Which lines will cause compilation error?

You had to select 2 option(s)

Q29. Given:

List strList = Arrays.asList("a", "aa", "aaa");
Function f = x->x.length();
Consumer c = x->System.out.print("Len:"+x+" ");
Predicate p = x->"".equals(x);
strList.forEach( *INSERT CODE HERE* );


What can be inserted in the code above?

You had to select 1 option(s)

Q30. Consider the following code:

import java.io.*;
public class Test
{
public static void main(String[] args) throws Exception
{
var fw = new FileWriter("text.txt");
// fw.write("hello"); //1
fw.close();
}
}

Which of the following statements are correct?

You had to select 1 option(s)

Q31. Which of these expressions will return true?

You had to select 4 option(s)

Q32. Identify correct statements about the following code:

You had to select 1 option(s)

Q33. Given:

interface Carnivore{
default int calories(List food){
return food.size()*100;
}
int eat(List foods);
}
class Tiger implements Carnivore{
public int eat(List foods){
System.out.println("Eating "+foods);
return foods.size()*200;
}
}
public class TestClass {
public static int size(List names){
return names.size()*2;
}
public static void process(List names, Carnivore c){
c.eat(names);
}

public static void main(String[] args) {
List fnames = Arrays.asList("a", "b", "c");
Tiger t = new Tiger();

INSERT CODE HERE

}
}

Which of the following options can be inserted independent of each other in the code above without any compilation error?

You had to select 3 option(s)

Q34. Given:

public class SimpleLoop {
public static void main(String[] args) {
int i=0, j=10;
var count = 0;
while (ii++;
j--;
count++;
}
System.out.println(i+" "+j+" "+count);
}
}

What is the result?

You had to select 1 option(s)

Q35. Consider that you are writing a set of classes related to a new Data Transmission Protocol and have created your own exception hierarchy derived from java.lang.Exception as follows:

nthu.trans.ChannelException
+-- enthu.trans.DataFloodingException
+-- enthu.trans.FrameCollisionException
(Both enthu.trans.DataFloodingException and enthu.trans.FrameCollisionException extend ChannelException)

You have a TransSocket class that has the following method:
long connect(String ipAddr) throws ChannelException

Now, you also want to write another "AdvancedTransSocket" class, derived from "TransSocket" which overrides the above mentioned method. Which of the following are valid declaration of the overriding method?

You had to select 2 option(s)

Q36. As a part of an application, you have serialized and stored some objects of a class in the database. At another place in the same application, you deserialize those objects.

After a few months you determine that you need to add one new String field in the class.

Which of the following statements are correct regarding the above described situation?

You had to select 1 option(s)

Q37. What would be the result of trying to compile and run the following program?

public class Test{
int[] ia = new int[1];
Object oA[] = new Object[1];
boolean bool;
public static void main(String args[]){
var test = new Test();
System.out.println(test.ia[0] + " " + test.oA[0]+" "+test.bool);
}
}

You had to select 1 option(s)

Q38. You have created a module named mycompany.smartschool packaged in smartschool.jar. This module uses a third party non-modular java library packaged as utils.jar.

How will you execute your module's main class named mycompany.smartschool.Main?

(Assume that the jar files are located in the current directory.)

You had to select 1 option(s)

Q39. Given:

public class Student {
private String name;
private int marks;
public Student(String name, int marks){
this.name = name;
this.marks = marks;
}
public String toString(){
return name+":"+marks;
}
//getters and setters not shown
}

What can be inserted in the code below so that it will print:
{20=[S1:20, S3:20], 30=[S3:30]}


List ls = Arrays.asList(new Student("S1", 20),
new Student("S3", 30), new Student("S3", 20) );

//INSERT CODE HERE
System.out.println(grouping);

You had to select 1 option(s)

Q40. A developer has written the following code snippet:

Console c = System.console(); //1
String line = c.readLine("Please enter your name:"); //2
System.out.println("Hello, "+line); //3

Which of the following statements are true about this code if it is run in the background by a scheduler?

You had to select 1 option(s)

Q41. Which statements regarding the following code are correct?

class A extends Thread
{
public void run()
{
System.out.println("Starting loop");
try{
Thread.sleep(10000); //1 sleep for 10 secs
}catch(Exception e){ e.printStackTrace(); }
System.out.println("Ending loop");
}
}
public class TestClass
{
public static void main(String args[]) throws Exception
{
A a = new A();
a.start();
Thread.sleep(1000);
a.interrupt();
}
}

You had to select 2 option(s)

Q42. Given that the file test.txt is accessible and contains multiple lines, which of the following code fragments will correctly print all the lines from the file?

You had to select 2 option(s)

Q43. Which of the following is/are valid instantiations and initializations of a multi dimensional array?

You had to select 2 option(s)

Q44. Consider the following code:

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

public class TestClass
{
public static void main(String[] args) throws Exception
{
double amount = 53000.35;

Locale jp = new Locale("jp", "JP");

//1 create formatter here.

System.out.println( formatter.format(amount) );
}
}

How will you create formatter using a factory at //1 so that the output is in Japanese Currency format?

You had to select 2 option(s)

Q46. Given:

public class TestClass
{
public static void main(String args[])
{
A ab = new B();
A ac = new C();

if( ac instanceof B b1){
b1.b();
if(b1 instanceof C c1){
c1.c();
}
}else{
ac.a();
}
}
}

class A {
void a(){ System.out.println("a"); }
}
class B extends A {
void b(){ System.out.println("b"); }
}
class C extends B {
void c(){ System.out.println("c"); }
}


What will be the output?

You had to select 1 option(s)

Q46. Which of the following are true regarding overloading of a method?

You had to select 1 option(s)

Q47. What will the following code print?

IntStream is = IntStream.range(1, 6);
IntStream is2 = is.takeWhile(x-> x%2==0);
is2.forEach(System.out::print);

You had to select 1 option(s)

Q48. Given:

String INPUT_FILE = "c:\\temp\\src\\foo.bar\\module-info.java";

Assuming the file exists, which of the following options will print the contents of the file?

You had to select 2 option(s)

Q49. What will the following method print?

public static void iCanDoThis(){
int x = 2;
int y = ~x; //LINE 2
int z = x ^ y; //LINE 3

boolean flag = x z++; //LINE 4

if(flag) {
flag = x > y && x > --z; //LINE 6
}

if(z>-1){ //LINE 8
--z;
} else z++;

System.out.println(flag+" "+z); //LINE 11
}

You had to select 1 option(s)

Q50. Given the following code:

enum Title
{
MR("Mr. "), MRS("Mrs. "), MS("Ms. ");
private String title;
private Title(String s){
title = s;
}
public String format(String first, String last){
return title+" "+first+" "+last;
}
}

//INSERT CODE HERE


Identify valid code snippets ..

(Assume that Title is accessible wherever required.)

You had to select 4 option(s)

Q51. What will the following code print when compiled and run?

Collection col = new HashSet();
col.add(1);
var list1 = List.of(col); //1
col.add(2); //2
var list2 = List.copyOf(col); //3
System.out.println(list1+", "+list2);

You had to select 1 option(s)

Q52. Which of the following are valid at line 1?

public class X{
//line 1: insert code here.
}

You had to select 2 option(s)

Q53. Which of the following declarations is equivalent to var b = 10>11;.

You had to select 2 option(s)

Q54. Given:

module foo.filter{
requires api;
provides api.Filter with foo.DoNothingFilter;
}

Assuming that api.Filter is an interface with just a single method List filter(List l), which of the following is a valid implementation of foo.DoNothingFilter class?

You had to select 1 option(s)

Q55. What will the following code print?

enum AccountType{
CHECKING("Checking account"), SAVINGS("Savings account"),
FD("Fixed Deposit");

private String desc;
AccountType(String desc){
this.desc = desc;
}

@Override
public String toString(){
return "Acct type:"+super.toString();
}

}

public class TestClass {
public static void main(String[] args) {
var at = AccountType.valueOf("FD");
System.out.println(at.ordinal()+" "+at);
}
}

You had to select 1 option(s)