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. Which one of the following classes is best suited for storing timestamp values of application events in a file? java.time.ZoneId class java.time.Duration class java.time.Instant class java.time.ZoneOffset class java.time.Period class 2 / 56 2. 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 #1. This program results in throwing a NullPointerException. This program results in a compiler error in statement #2. 3 / 56 3. Which method is used to start a thread in Java? run() init() start() execute() 4 / 56 4. What is the output of the following code?int[] arr = {1, 2, 3, 4, 5};System.out.println(arr[2]); 1 4 3 2 5 / 56 5. 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 filter elements based on a flat structure To map each element to a new value To merge multiple streams into one 6 / 56 6. 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 // 1 An exception occurs at runtime Compilation fails on the line marked as // 2 1.0 7 / 56 7. What does the following lambda expression represent?() -> {} None of the above A lambda that accepts two parameters and does nothing A lambda that does nothing and returns void A lambda that throws an exception 8 / 56 8. 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 [20, 20] Compilation fails on the line marked as // 2 An exception occurs at runtime 9 / 56 9. Which of the following is a checked exception? ArrayIndexOutOfBoundsException NullPointerException ArithmeticException IOException 10 / 56 10. Which of these collectors is used for grouping elements of a Stream? Collectors.toSet() Collectors.toList() Collectors.groupingBy() Collectors.joining() 11 / 56 11. Which of these is a terminal operation in the Stream API? filter forEach flatMap map 12 / 56 12. Which of the following are valid ChronoField values for LocalDate? Both A & C MILLI_OF_SECOND HOUR_OF_DAY DAY_OF_WEEK DAY_OF_MONTH 13 / 56 13. 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); }} 115110 27 1105110 11511 14 / 56 14. Which one of the following options correctly describes the behavior of this program? The program does not compile and fails with multiple compiler errors. When executed, the program prints “Worker ” and then terminates. When executed, the program throws an IllegalMonitorStateException. When executed, the program prints “Worker ”, and after that the program hangs (i.e., does not terminate). When executed, the program prints the following: “Worker Master ”. 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. What is the main purpose of the Stream.sorted method? To remove duplicate elements from the stream 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 17 / 56 17. In which of the following type of ResultSet, the cursor can only move forward in the result set? ResultSet.TYPE_SCROLL_INSENSITIVE ResultSet.TYPE_SCROLL_SENSITIVE ResultSet.TYPE_FORWARD_ONLY None of the above. 18 / 56 18. What will be the output of the following code?String str = "Hello";str.concat(" World");System.out.println(str); Compilation Error Hello World Hello World 19 / 56 19. Which of the following statements are true? Lambda expressions don't return values A return keyword is always optional in a lambda expression Curly brackets are required whenever the return keyword is used in a lambda expression A return keyword is always required in a lambda expression 20 / 56 20. What type of operation is Stream.filter? Source Terminal Mutable Intermediate 21 / 56 21. 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 run oops in start oops in run oops in constructor oops in start oops in constructor oops in constructor oops in start oops in run oops 22 / 56 22. Which of the following state(s) is/are NOT legitimate thread state(s)? (Select all that apply.) EXECUTING WAITING NEW RUNNABLE TERMINATED 23 / 56 23. Which method is used to compare two strings, ignoring case considerations? compareTo() equals() equalsIgnoreCase() compareToIgnoreCase() 24 / 56 24. 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 equal s1 and s3 equal s1 and s2 not equal s1 and s3 not equal s1 and s2 equal s1 and s3 not equal s1 and s2 not equal s1 and s3 equal 25 / 56 25. 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 26 / 56 26. Lambda expressions can be used with the Java Collections API primarily in ... Sorting All of the above Filtering Iterating 27 / 56 27. Which method is used to transform each element of a Stream using a provided function? map reduce filter flatMap 28 / 56 28. Which of the following statements correctly describes the behavior of this program? This program will throw a NullPointerException. This program will result in a compiler error. This program will print null in the console. This program will print 10 in the console. 29 / 56 29. 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)); }} Compile-time error true ClassCastException at runtime false 30 / 56 30. Which of the following are valid ChronoUnit values for LocalTime? Both B & D YEAR HALF_DAYS NANOS DAY 31 / 56 31. 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");} Exception caught Finally block Finally block Exception caught 32 / 56 32. Which method is used to start the execution of a thread? begin() run() start() execute() 33 / 56 33. 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 }} None null NullPointerException NullPointerException NullPointerException null null 34 / 56 34. 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 Thread-1 Thread-2 main main Thread-0 main Thread-0 Thread-1 Thread-0 main Thread-1 35 / 56 35. Which of the following is correct about PreparedStatement? PreparedStatement allows mapping different requests with same prepared statement but different arguments to execute the same execution plan. Prepared statements are more secure because they use bind variables, which can prevent SQL injection attack. None of the above. Both of the above. 36 / 56 36. 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 and will print “Running” in the console. 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. 37 / 56 37. What is the result of applying the Stream.reduce operation? An Optional describing the reduced value, if any A new stream with elements reduced according to a provided accumulator function A boolean indicating if any stream elements match a given predicate A list of elements that were reduced 38 / 56 38. What is the purpose of the join() method in Java threads? To interrupt the execution of a thread. To schedule the execution of a thread. To wait for a thread to finish its execution. To notify a thread to stop execution. 39 / 56 39. What is the purpose of the wait() method in Java threads? To notify other threads to resume execution. To pause the execution of a thread. To terminate a thread. To release the lock held by the thread. 40 / 56 40. 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]; 41 / 56 41. You cannot use ... inside lambda expressions. this keyword arithmetic operations return statement break and continue 42 / 56 42. Which of the following keywords is used to manually throw an exception? throws catch throw try 43 / 56 43. Which method is used to transform each element of a Stream using a provided function? filter flatMap map reduce 44 / 56 44. Which of the following methods can be used to make a thread pause execution for a specific amount of time? wait() sleep() yield() pause() 45 / 56 45. 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 September Friday F 46 / 56 46. Which of the following is correct about setFetchSize(int)? setFetchSize(int) affects how the database returns the ResultSet data. None of the above. setFetchSize(int) defines the number of rows that will be read from the database when the ResultSet needs more rows. Both of the above. 47 / 56 47. How can synchronization be achieved in Java threads? Using the synchronized keyword. Using the final keyword. Using the static keyword. Using the volatile keyword. 48 / 56 48. Which of the following type of JDBC driver, uses database native protocol? Native-API, partly Java driver JDBC-ODBC Bridge plus ODBC driver JDBC-Net, pure Java driver Native-protocol, pure Java driver 49 / 56 49. What is the main advantage of multithreading in Java? Elimination of runtime errors. Improved program performance. Reduced memory usage. Simplified program structure. 50 / 56 50. Which of the following is correct about Statement class of JDBC? Statement encapsulates an SQL statement which is passed to the database to be parsed and compiled. Both of the above. Statement encapsulates an SQL statement which is passed to the database to be planned and executed. none of the above. 51 / 56 51. 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: In the run method; the thread name is: thread-0 In the main method; the thread name is: main The program results in a compiler error at statement #1. The program prints the following: In run method; thread name is: main In main method; thread name is: main 52 / 56 52. 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(); }} This program will always print the following: Tennis Tennis Table Table. This program will always print the following: Table Table Tennis Tennis. The output of this program cannot be predicted; it depends on thread scheduling. This program will throw an IllegalStateException. 53 / 56 53. Select all the classes that extend the String class StringWriter None StringBuffer StringBuilder 54 / 56 54. What is the default priority of a thread in Java? 10 1 0 5 55 / 56 55. What does the Stream.peek method do? Performs an action on each element of the stream without modifying it Consumes and removes an element from the stream Reduces the stream to a single summary element Filters elements based on a predicate 56 / 56 56. 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. There is no fixed limit. It depends on the amount of available memory. Your score is 0%
