Java Quizz Dive into our tech quiz zone and put your technical skills to the test! Our quizzes cover a wide array of technical topics, perfect for sharpening your knowledge and challenging your understanding. Compete with others, see your rankings, and boost your technical proficiency. Start quizzing today! 1 / 56 1. What is the output of the following code?int[] arr = {1, 2, 3, 4, 5};System.out.println(arr[2]); 1 2 4 3 2 / 56 2. What is the result of applying the Stream.reduce operation? A boolean indicating if any stream elements match a given predicate A new stream with elements reduced according to a provided accumulator function An Optional describing the reduced value, if any A list of elements that were reduced 3 / 56 3. What will be the output of the below statements?public class Test { public static void main(String[] args) { String s1 = "abc"; StringBuffer s2 = new StringBuffer(s1); System.out.println(s1.equals(s2)); }} true false Compile-time error ClassCastException at runtime 4 / 56 4. Which of the following methods can be used to make a thread pause execution for a specific amount of time? yield() pause() sleep() wait() 5 / 56 5. Consider the following program:public class StrEqual { public static void main(String[] args) { String s1 = "hello"; String s2 = new String("hello"); String s3 = "hello"; if (s1 == s2) { System.out.println("s1 and s2 equal"); } else { System.out.println("s1 and s2 not equal"); } if (s1 == s3) { System.out.println("s1 and s3 equal"); } else { System.out.println("s1 and s3 not equal"); } }}Which one of the following options provides the output of this program when executed? s1 and s2 not equal s1 and s3 equal s1 and s2 equal s1 and s3 equal s1 and s2 not equal s1 and s3 not equal s1 and s2 equal s1 and s3 not equal 6 / 56 6. Consider this code segment?DateTimeFormatter formatter =DateTimeFormatter.ofPattern("EEEE", Locale.US);System.out.println(formatter.format(LocalDateTime.now()));Which of the following outputs matches the string pattern "EEEE" given in this code segment? Sept Friday F September 7 / 56 7. What is the output of the following program?public class Question { T t; public static void main(String[] args) { Question q = new Question(); // 1 q.t = new Float(1); // 2 System.out.println(q.t); }} Compilation fails on the line marked as // 2 An exception occurs at runtime 1.0 Compilation fails on the line marked as // 1 8 / 56 8. Which of the following statements are true? Curly brackets are required whenever the return keyword is used in a lambda expression A return keyword is always optional in a lambda expression Lambda expressions don't return values A return keyword is always required in a lambda expression 9 / 56 9. Which of the following keywords is used to manually throw an exception? try throw throws catch 10 / 56 10. What is the main advantage of multithreading in Java? Elimination of runtime errors. Improved program performance. Simplified program structure. Reduced memory usage. 11 / 56 11. Lambda expressions can be used with the Java Collections API primarily in ... Filtering Sorting All of the above Iterating 12 / 56 12. What is the main purpose of the Stream.sorted method? To reverse the order of elements in the stream To randomly shuffle the elements of the stream To sort the elements of the stream in their natural order or by a provided comparator To remove duplicate elements from the stream 13 / 56 13. What is the purpose of the Stream.flatMap method? To replace each element with a stream and then flatten the streams into a single stream To merge multiple streams into one To filter elements based on a flat structure To map each element to a new value 14 / 56 14. Which method is used to start a thread in Java? run() start() execute() init() 15 / 56 15. Which of the following is a valid lambda expression? x -> x*x (int x, int y) -> x + y All of the above (x, y) -> return x + y; 16 / 56 16. Consider the following program and choose the right option:class MyThread extends Thread { public void run() { System.out.println("Running"); }}public class ThreadTest { public static void main(String args[]) throws InterruptedException { Runnable r = new MyThread(); // #1 Thread myThread = new Thread(r); // #2 myThread.start(); }} The program will compile with no errors but does not print any output in the console. The program will result in a compilation error at statement #2. The program will result in a compilation error at statement #1. The program will compile with no errors and will print “Running” in the console. 17 / 56 17. Consider the following program and predict the output:public class Test { public static void main(String[] args) { String s = new String("5"); System.out.println(1 + 10 + s + 1 + 10); }} 27 1105110 11511 115110 18 / 56 18. Which of the following correctly declares an array of integers in Java? int[] arr; All of the above int arr[]; int arr = new int[10]; 19 / 56 19. Consider the following program and predict the output:class MyThread extends Thread { public MyThread(String name) { this.setName(name); start(); System.out.println("in constructor " + getName()); } @Override public void start() { System.out.println("in start " + getName()); } public void run() { System.out.println("in run " + getName()); }}public class ThreadTest { public static void main(String[] args) { new MyThread("oops"); }} in start oops in constructor oops in start oops in constructor oops in run oops in start oops in run oops in constructor oops in constructor oops in start oops in run oops 20 / 56 20. Which of the following statements correctly describes the behavior of this program? This program will print null in the console. This program will print 10 in the console. This program will throw a NullPointerException. This program will result in a compiler error. 21 / 56 21. Which of these is a terminal operation in the Stream API? map filter forEach flatMap 22 / 56 22. What is the purpose of the wait() method in Java threads? To pause the execution of a thread. To release the lock held by the thread. To notify other threads to resume execution. To terminate a thread. 23 / 56 23. What is the output of the following program?public class Question { public static void main(String[] args) { Question q = new Question(); List l = new ArrayList(); l.add(20); l.add(30); q.m1(l); } private void m1(List l) { m2(l); // 1 } private void m2(List l) { l.set(1, l.get(0)); // 2 System.out.println(l); }} Compilation fails on the line marked as // 1 Compilation fails on the line marked as // 2 [20, 20] An exception occurs at runtime 24 / 56 24. Which of the following is a checked exception? IOException ArrayIndexOutOfBoundsException ArithmeticException NullPointerException 25 / 56 25. How can synchronization be achieved in Java threads? Using the final keyword. Using the static keyword. Using the volatile keyword. Using the synchronized keyword. 26 / 56 26. Which of the following is correct about PreparedStatement? Prepared statements are more secure because they use bind variables, which can prevent SQL injection attack. PreparedStatement allows mapping different requests with same prepared statement but different arguments to execute the same execution plan. None of the above. Both of the above. 27 / 56 27. Consider the following program and choose the correct answer:class MyThread extends Thread { public MyThread(String name) { this.setName(name); } @Override public void run() { try { sleep(100); } catch (InterruptedException e) { e.printStackTrace(); } play(); } private void play() { System.out.print(getName()); System.out.print(getName()); }}public class ThreadTest { public static void main(String args[]) throws InterruptedException { Thread tableThread = new MyThread("Table"); Thread tennisThread = new MyThread("Tennis"); tableThread.start(); tennisThread.start(); }} The output of this program cannot be predicted; it depends on thread scheduling. This program will throw an IllegalStateException. This program will always print the following: Tennis Tennis Table Table. This program will always print the following: Table Table Tennis Tennis. 28 / 56 28. What is the purpose of the join() method in Java threads? To notify a thread to stop execution. To wait for a thread to finish its execution. To interrupt the execution of a thread. To schedule the execution of a thread. 29 / 56 29. Which of these collectors is used for grouping elements of a Stream? Collectors.toSet() Collectors.toList() Collectors.groupingBy() Collectors.joining() 30 / 56 30. Which of the following is correct about setFetchSize(int)? setFetchSize(int) defines the number of rows that will be read from the database when the ResultSet needs more rows. Both of the above. setFetchSize(int) affects how the database returns the ResultSet data. None of the above. 31 / 56 31. Select all the classes that extend the String class StringBuilder None StringBuffer StringWriter 32 / 56 32. Which method is used to transform each element of a Stream using a provided function? filter map reduce flatMap 33 / 56 33. Which of the following type of JDBC driver, uses database native protocol? JDBC-ODBC Bridge plus ODBC driver JDBC-Net, pure Java driver Native-protocol, pure Java driver Native-API, partly Java driver 34 / 56 34. What type of operation is Stream.filter? Intermediate Source Terminal Mutable 35 / 56 35. Which one of the following classes is best suited for storing timestamp values of application events in a file? java.time.Period class java.time.Instant class java.time.Duration class java.time.ZoneId class java.time.ZoneOffset class 36 / 56 36. What does the Stream.peek method do? Filters elements based on a predicate Consumes and removes an element from the stream Performs an action on each element of the stream without modifying it Reduces the stream to a single summary element 37 / 56 37. Which method is used to transform each element of a Stream using a provided function? flatMap filter map reduce 38 / 56 38. Consider the following program and predict the output:class MyThread implements Runnable { @Override public void run() { System.out.println(Thread.currentThread().getName()); }}public class ThreadTest { public static void main(String arg[]) { Thread thread = new Thread(new MyThread()); thread.run(); thread.run(); thread.start(); }} Thread-0 main Thread-1 main Thread-0 Thread-1 main main Thread-0 Thread-0 Thread-1 Thread-2 39 / 56 39. Which of the following is correct about Statement class of JDBC? Statement encapsulates an SQL statement which is passed to the database to be planned and executed. Both of the above. none of the above. Statement encapsulates an SQL statement which is passed to the database to be parsed and compiled. 40 / 56 40. Which of the following state(s) is/are NOT legitimate thread state(s)? (Select all that apply.) WAITING TERMINATED RUNNABLE EXECUTING NEW 41 / 56 41. Which method is used to start the execution of a thread? begin() execute() start() run() 42 / 56 42. What will be the output of the following code?String str = "Hello";str.concat(" World");System.out.println(str); Compilation Error World Hello World Hello 43 / 56 43. What will be the output of the below statements?public class Test { public static void main(String[] args) { String s1 = null; System.out.println(s1); //line 2 System.out.println(s1.toString()); //line 3 }} null NullPointerException null null NullPointerException NullPointerException None 44 / 56 44. What is the default priority of a thread in Java? 5 0 10 1 45 / 56 45. Which of the following are valid ChronoUnit values for LocalTime? YEAR HALF_DAYS NANOS Both B & D DAY 46 / 56 46. You cannot use ... inside lambda expressions. break and continue arithmetic operations this keyword return statement 47 / 56 47. What is the maximum number of threads that can be created in a Java program? It is limited to 100 threads. It depends on the number of CPU cores. It depends on the amount of available memory. There is no fixed limit. 48 / 56 48. Which one of the following options correctly describes the behavior of this program? When executed, the program prints the following: “Worker Master ”. When executed, the program throws an IllegalMonitorStateException. The program does not compile and fails with multiple compiler errors. When executed, the program prints “Worker ” and then terminates. When executed, the program prints “Worker ”, and after that the program hangs (i.e., does not terminate). 49 / 56 49. In which of the following type of ResultSet, the cursor can only move forward in the result set? ResultSet.TYPE_FORWARD_ONLY ResultSet.TYPE_SCROLL_SENSITIVE ResultSet.TYPE_SCROLL_INSENSITIVE None of the above. 50 / 56 50. GivenList list = new ArrayList(); // 1list.add(new Integer(2)); // 2list.add(new Object()); // 3Which line will generate a compile-time error? Line marked as // 1 Line marked as // 3 No compile-time error is generated Line marked as // 2 51 / 56 51. Consider the following program and predict its output:public class Test { public static void main(String[] args) { String str = null; switch (str) { // #1 case "null": System.out.println("null string"); // #2 break; } }} This program prints the following: null string. This program results in a compiler error in statement #2. This program results in throwing a NullPointerException. This program results in a compiler error in statement #1. 52 / 56 52. What does the following lambda expression represent?() -> {} A lambda that does nothing and returns void A lambda that accepts two parameters and does nothing None of the above A lambda that throws an exception 53 / 56 53. Consider the following program and predict the output:class MyThread extends Thread { @Override public void run() { System.out.println("In run method; thread name is: " + Thread.currentThread().getName()); }}public class ThreadTest { public static void main(String args[]) { Thread myThread = new MyThread(); myThread.run(); // #1 System.out.println("In main method; thread name is: " + Thread.currentThread().getName()); }} The program results in a runtime exception. The program prints the following: In run method; thread name is: main In main method; thread name is: main The program results in a compiler error at statement #1. The program prints: In the run method; the thread name is: thread-0 In the main method; the thread name is: main 54 / 56 54. Which of the following are valid ChronoField values for LocalDate? HOUR_OF_DAY DAY_OF_WEEK Both A & C DAY_OF_MONTH MILLI_OF_SECOND 55 / 56 55. Which method is used to compare two strings, ignoring case considerations? compareToIgnoreCase() compareTo() equals() equalsIgnoreCase() 56 / 56 56. What is the output of the following code?try { int a = 10 / 0;} catch (ArithmeticException e) { System.out.println("Exception caught");} finally { System.out.println("Finally block");} Finally block Finally block Exception caught Exception caught Your score is 0%
