Thread Java - MCQ set 1 (20 questions, 43 marks)

Q1 - Q2, 2 EASY level difficulty questions 1 mark each. 1 * 2 = 2 marks 


1. What is true about threads?

a.Threads consumes CPU in best possible manner
b.Threads enables multi processing.
c.Multi threading reduces idle time of CPU
d.All


2. A thread can acquire a lock by using which reserved keyword?

a.volatile
b.synchronized
c.locked
d.none



Q3 - Q15, 13 MEDIUM level difficulty questions 2 mark each. 2 * 13 = 26 marks


3. How many threads can a process contain?

a.1
b.2
c.multiple
d.none


4. What is sometimes also called a lightweight process?

a.Thread
b.Process
c.JVM
d.


5. What are valid points about thread

a.Thread are subdivision of Process.
b.One or more Threads runs in the context of process.
c.Threads can execute any part of process. And same part of process can be executed by multiple Threads.
d.All


6. What are valid point about processes

a.Processes have their own copy of the data segment of the parent process
b.Threads have direct access to the data segment of its process
c.Processes have their own address
d.All of these


7. Which is thread safe?

a.StringBuffer
b.StringBuilder
c.All
d.None


8. How can we create Thread

a.By Extending Thread class
b.Implementing Runnable interface
c.By using Executor framework - which can internally form threads
d.All


9. Which of these is not a Thread state?

a.New
b.Runnable
c.sleep
d.terminated


10. synchronized instance methods acquire lock on?

a.object
b.class
c.All
d.None


11. What state does Thread enter in when it has been created and started?

a.New
b.Runnable
c.Running
d.Waiting


12. Which method can be used to find whether Thread hasn't entered dead state?

a.isAlive()
b.isRunning()
c.isNotDead
d.All


13. What is valid about threads

a.Threads have their own heap allocated area.
b.Threads have their own stack.
c.Threads doesn't have own stack.
d.None


14. How can you ensure all threads that started from main must end in order in which they started and also main should end in last

a.join() method
b.sleep() method
c.wait() method
d.run() method


15. Which of these is valid about threads in java

a.Thread behaviour is unpredictable
b.execution of Threads depends on Thread scheduler
c.Same threading program may produce different output in subsequent executions even on same platform
d.All



Q16 - Q20, 5 HARD level difficulty questions 3 mark each.       3 * 5 = 15 marks


16. Which method restarts the thread

a.start()
b.restart()
c.restartThread()
d.none


17. What is true about acquiring object lock before calling wait(), notify() and notifyAll()?

a.it’s mandatory to acquire object lock before calling wait(), notify() and notifyAll() methods on object
b.If we call wait(), notify() and notifyAll() methods without acquiring object lock i.e. from outside synchronize block then java.lang.IllegalMonitorStateException is thrown at runtime.
c.wait(), notify() and notifyAll() methods are always called from Synchronized block only
d.all


18. What is difference between starting thread with run() and start() method?

a.There is no difference
b.When you call start() method, main thread internally calls run() method to start newly created Thread
c.run() calls start() method internally
d.None


19. What are valid statements for suspend() and resume() method?

a.Suspend() method is deadlock prone.
b.If the target thread holds a lock on object when it is suspended, no thread can lock this object until the target thread is resumed.
c.If the thread that would resume the target thread attempts to lock this monitor prior to calling resume, it results in deadlock formation.
d.All


20. How can Thread go from waiting to runnable state?

a.notify/notifAll
b.When sleep time is up
c.Using resume() method when thread was suspended
d.All

Quiz 1 - Correct answers

EASY
1) d
2) b

MEDIUM
3) c
4) a
5) d
6) d
7) a
8) d
9) c
10) a
11) c
12) a
13) b
14) a
15) d

HARD
16) d
17) d
18) b
19) d
20) d

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Thread Java - MCQ set 2 (20 questions, 43 marks)

Q1 - Q2, 2 EASY level difficulty questions 1 mark each. 1 * 2 = 2 marks 


1. wait(), notify() & notifyAll() are methods of which class or interface?

a.Thread class
b.Runnable interface
c.Object
d.None


2. When start() method is called on thread it enters ______ state.

a.running
b.runnable
c.new
d.waiting



Q3 - Q15, 13 MEDIUM level difficulty questions 2 mark each. 2 * 13 = 26 marks


3. What is time slicing in threads

a.In time slicing, a thread executes for a certain predefined time and then enters runnable pool.
b.Thread in runnable pool can enter running state when selected by thread scheduler.
c.All
d.None


4. Significance of Volatile keyword in java

a.If a field is declared volatile, in that case the Java memory model ensures that all threads see a consistent value for the variable.
b.Volatile caches methods
c.All of these
d.None


5. What is name of thread which calls main method

a.mainThread
b.Thread
c.Thread-0
d.main


6. Significance of synchronized variable

a.synchronized variable doesn't exist
b.synchronized variable are used in multi threading environment
c.Prevents concurrent access to variables
d.None


7. What is pre-emptive scheduling in threads

a.In pre-emptive scheduling, the highest priority thread executes until it enters into the waiting or dead state
b.In pre-emptive scheduling, the low priority thread executes until it enters into the waiting or dead state
c.In pre-emptive scheduling, the medium priority thread executes until it enters into the waiting or dead state
d.Anyone may happen


8. What will happen if two threads try to read same resource without synchronization in java

a.It is not allowed in java
b.It doesn't create any race condition
c.Will create race condition
d.None


9. What are valid statements for daemon threads?

a.User created threads are non daemon threads.
b.JVM can exit when only daemon threads exist in system.
c.Daemon threads are low priority threads which runs intermittently in background for doing garbage collection.
d.All of these


10. What will happen if two threads try to write to same resource without synchronization in java

a.It is not allowed in java
b.It doesn't create any race condition
c.It will create race condition
d.None


11. How to use volatile methods in java?

a.Prevents concurrent access to shared resources
b.volatile methods are used in non-multithreading environment
c.volatile methods doesn't exist
d.None


12. Which tools could be used to analyse thread dumps

a.VisualVM
b.jstack
c.All
d.none


13. Which method can make Thread to go from running to waiting state

a.wait()
b.resume()
c.notify()
d.alive()


14. How Can we acquire lock on class?

a.By acquiring lock on variables.
b.By acquiring lock on instance variables.
c.By acquiring lock on static method
d.By acquiring lock on instance method


15. What are valid statements for sleep method?

a.when sleep() is called on thread it goes from running to waiting state and can return to runnable state when sleep time is up.
b.sleep() is a static method, causes the currently executing thread to sleep for the specified number of milliseconds.
c.thread need not to to acquire object lock before calling sleep() method
d.All



Q16 - Q20, 5 HARD level difficulty questions 3 mark each.       3 * 5 = 15 marks


16. Which method can make Thread to go from running to waiting state?

a.wait()
b.sleep()
c.suspend()
d.All


17. What are valid statements for yield method?

a.yield() method when called on thread gives a hint to the thread scheduler that the current thread is willing to yield its current use of a processor. The thread scheduler is free to ignore this hint.
b.yield() method stops thread for unpredictable time.
c.yield() is a static method, hence calling Thread.yield() causes currently executing thread to yield.
d.All


18. What are valid statements about Constructor and synchronization in java?

a.We can enclose constructor in try-catch block
b.We can use use synchronized code in constructor
c.Constructor can be synchronized
d.None


19. Which method can be used to find that thread holds lock

a.holdLock()
b.lockHold()
c.holdsLock(object)
d.lockHold(object)


20. What is addShutdownHook method in java

a.addShutdownHook method registers a new virtual-machine shutdown hook.
b.A shut down hook is a uninitialized and unstated thread.
c.When JVM initialises it will start all registered shutdown hooks
d.None

Quiz 2 - Correct answers

EASY
1) c
2) b

MEDIUM
3) c
4) a
5) d
6) a
7) a
8) b
9) d
10) c
11) c
12) c
13) a
14) c
15) d

HARD
16) d
17) d
18) b
19) c
20) a

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Thread Java - MCQ set 3 (20 questions, 43 marks)

Q1 - Q2, 2 EASY level difficulty questions 1 mark each. 1 * 2 = 2 marks 


1. Can multiple threads exist on one object?

a.Multiple threads can exist on same object
b.Multiple threads cannot exist on same object
c.Only 2 threads can exist on same object
d.None


2. What is deadlock in java?

a.Deadlock is a situation where two threads on same object are waiting for each other to release lock holded by them on resources
b.Deadlock is a situation where threads on different object are waiting for each other to release lock holded by them on resources
c.None



Q3 - Q15, 13 MEDIUM level difficulty questions 2 mark each. 2 * 13 = 26 marks


3. Which method can be used to handle uncaught runtime exception generated in run method?

a.exceptionHandler()
b.defaultExceptionHandler()
c.setDefaultUncaughtExceptionHandler()
d.catchException()


4. What is valid statement about ThreadGroup

a.When program starts JVM creates a ThreadGroup named main
b.Unless specified, all newly created threads become members of the main thread group
c.All
d.None


5. What is minimum thread priority in java?

a.-1
b.0
c.1
d.5


6. What is maximum thread priority

a.10
b.12
c.5
d.8


7. What will be output of following code -
   
   

a.start main() method
        end main() method
        i=0 ,ThreadName=Thread-0
        i=0 ,ThreadName=Thread-1
        i=1 ,ThreadName=Thread-0
        i=2 ,ThreadName=Thread-0
        i=1 ,ThreadName=Thread-1
        i=2 ,ThreadName=Thread-1
        (Output may vary)
b.start main() method
        i=0 ,ThreadName=Thread-0
        i=0 ,ThreadName=Thread-1
        i=1 ,ThreadName=Thread-0
        i=2 ,ThreadName=Thread-0
        i=1 ,ThreadName=Thread-1
        i=2 ,ThreadName=Thread-1
        (Output may vary)
c.end main() method
        start main() method
        i=0 ,ThreadName=Thread-0
        i=0 ,ThreadName=Thread-1
        i=1 ,ThreadName=Thread-0
        i=2 ,ThreadName=Thread-0
        i=1 ,ThreadName=Thread-1
        i=2 ,ThreadName=Thread-1
        (Output may vary)
d.None


8. What will be output of following code -
   
   

a.In main() method
        i=0 ,ThreadName=Thread-0
        i=1 ,ThreadName=Thread-0
        i=0 ,ThreadName=Thread-1
        i=2 ,ThreadName=Thread-0
        i=1 ,ThreadName=Thread-1
        end main() method
        i=2 ,ThreadName=Thread-1
b.In main() method
        i=0 ,ThreadName=Thread-0
        i=1 ,ThreadName=Thread-0
        i=0 ,ThreadName=Thread-1
        i=2 ,ThreadName=Thread-0
        i=1 ,ThreadName=Thread-1
        i=2 ,ThreadName=Thread-1
        end main() method
c.In main() method
        i=0 ,ThreadName=Thread-0
        i=1 ,ThreadName=Thread-0
        i=2 ,ThreadName=Thread-0
        i=0 ,ThreadName=Thread-1
        i=1 ,ThreadName=Thread-1
        i=2 ,ThreadName=Thread-1
        end main() method
d.None


9. What will be output of following code -
   
   
   

a.Thread-1 ENDED
        x
        press enter
       
b.press enter
        x
        x
        x
        x
       
        Thread-1 ENDED
        ( thread1 will keep on printing x until enter is pressed)
c.Thread-1 ENDED
        press enter
        x
d.None


10. What will be output of following code -
    
    
    

a.1
b.2
c.Exception will be thrown
d.None


11. What will be output of following code -
    
    
    

a.Consumer waiting for production to get over.
        Consumed : 1
        Producer is still Producing, Produced : 1
        Producer is still Producing, Produced : 2
        Producer is still Producing, Produced : 3
        Production is over, consumer can consume.
       
        Consumed : 2
        Consumed : 3
b.Consumer waiting for production to get over.
        Producer is still Producing, Produced : 1
        Producer is still Producing, Produced : 2
        Producer is still Producing, Produced : 3
        Production is over, consumer can consume.
        Consumed : 1
        Consumed : 2
        Consumed : 3
c.None


12. What will be output of following code -
    
    
    

a.1
b.Nothing will be printed
c.Runtime exception will be thrown
d.1 2


13. What will be output of following code -
    
    
    

a.1 3 2 4
b.1 2 3 4
c.Runtime exception
d.(None of these)


14. What will be output of following code -
    
    
    

a.1 2
b.2 3
c.1 3
d.Compilation error


15. What will be output of following code -
    
    

a.Thread-1
        Thread-1
        Thread-2
        Thread-2
b.Thread-1
        Thread-2
        Thread-1
        Thread-2
c.Thread-1
        Thread-2
        Thread-2
        Thread-1
d.None



Q16 - Q20, 5 HARD level difficulty questions 3 mark each.       3 * 5 = 15 marks


16. What will be output of following code -
    
    
    

a.1
        4
b.1
        2
        3
        4
        5
c.1
        2
        4
        5
        3
d.4
        1


17. What will be output of following code -
    
    
    

a.main has started
        Thread-1 has started
        Thread-1 has ended
b.main has started
        Thread-1 has started
        main has ended
        Thread-1 has ended
       
c.main has started
        Thread-1 has started
        Thread-1 has ended
        main has ended
d.None


18. What will be output of following code -
    
    

a.RuntimeException will be thrown
b.1
c.2
d.Nothing will be printed


19. What will be output of following code -
    
    

a.Program will face compile time Exception
b.Thread-1 Thread-1 Thread-0 Thread-0
c.Program will face NullPointerException
d.None


20. What will be output of following code -
    
    
    

a.Thread-1 in synchronized void method1() started
        Thread-2 in synchronized void method2() started
        Thread-2 in synchronized void method2() ended
        Thread-1 in synchronized void method1() ended
b.Thread-1 in synchronized void method1() started
        Thread-1 in synchronized void method1() ended
        Thread-2 in synchronized void method2() started
        Thread-2 in synchronized void method2() ended
c.Thread-1 in synchronized void method1() started
        Thread-2 in synchronized void method2() started
        Thread-1 in synchronized void method1() ended
        Thread-2 in synchronized void method2() ended
d.None

Quiz 3 - Correct answers

EASY
1) a
2) a

MEDIUM
3) c
4) c
5) c
6) a
7) a
8) c
9) b
10) a
11) b
12) d
13) b
14) c
15) a

HARD
16) d
17) c
18) b
19) c
20) b