PROGRAMMING IN JAVA Assignment 6 | NPTEL | Answer with Explanation | Exception Handling MCQs
Test Your Java Fundamentals with a Challenging MCQ Assignment on " Exception Handling " Sharpen your core Java skills with this engaging multiple-choice quiz (MCQ). Designed for beginners, this Assignment 6 assesses your understanding of fundamental Java concepts. Whether you're new to programming or refreshing your knowledge, this MCQ [Java Exception Handling ] challenge is a perfect way to gauge your progress and identify areas for improvement.
Which of the following is NOT TRUE in Java?
a. Every thread has a priority.
b. JVM allows multiple threads of execution running concurrently.
c. Threads with higher priority are executed first.
d. You cannot set a maximum priority value that a thread can have.
Answer
d. You cannot set a maximum priority value that a thread can have.
A thread is a thread of execution in a program. The Java Virtual Machine allows an application to
have multiple threads of execution running concurrently. Every thread has a priority. Threads with
higher priority are executed in preference to threads with lower priority. The MAX_PRIORITY
field can be used to set priority value of a thread in Java.
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Consider the following piece of code.
class PrimeRun implements Runnable {
long minPrime;
PrimeRun(long minPrime) {
this.minPrime = minPrime;
}
public void run() {
// compute primes larger than minPrime
. . .
}
}Which of the following is TRUE regarding the above code?
a. Creating a thread in Java using Runnable interfaceb. Thread creation by declaring a class to be a subclass of Thread
c. Overriding the run method of class Thread
d. The class implements the run method.
Answer
a. Creating a thread in Java using Runnable interface,d. The class implements the run method.
There are two ways to create a new thread of execution. One is to declare a class to be a subclass of Thread. This subclass should override the run method of class Thread. An instance of the subclass can then be allocated and started. The other way to create a thread is to declare a class that implements the Runnable interface. That class then implements the run method. An instance of the class can then be allocated, passed as an argument when creating Thread, and started. The same example is given here.
Which of the following cannot be used to create an instance of Thread?
a. By implementing the Runnable interface.
b. By extending the Thread class.
c. By creating a new class named Thread and calling method run().
d. By importing the Thread class from the related package.
Answer
c. By creating a new class named Thread and calling method run().,d. By importing the Thread class from the related package.
An application that creates an instance of Thread must provide the code that will run in that thread.
There are two ways to do this:
●Provide a Runnable object. The Runnable interface defines a single method, run, meant to contain the code
executed in the thread. The Runnable object is passed to the Thread constructor
●Subclass Thread. The Thread class itself implements Runnable, though its run method does nothing. An
application can subclass Thread, providing its own implementation of run
Reference:https://docs.oracle.com/javase/tutorial/essential/concurrency/runthread.html
What is the use of sleep(long millis) function in Java?
a. Pauses the thread execution for exactly the given time with no dependency.b. Pauses the thread execution but depends on precision of system timers.
c. Pauses the thread execution but depends on precision of system schedulers.
d. Pauses the thread execution but depends on precision of both system timers and schedulers.
Answer
d. Pauses the thread execution but depends on precision of both system timers and schedulers.
The sleep(long millis) function causes the currently executing thread to sleep
(temporarily cease execution) for the specified number of milliseconds, subject to the precision
and accuracy of system timers and schedulers.
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Which method start() will do which of the following?
a. Causes this thread to begin execution.b. Either start the execution for new thread or pause an ongoing thread.
c. The JVM calls the run method of this thread.
d. Recovers a thread from deadlock and begin execution
Answer
a. Causes this thread to begin execution.,c. The JVM calls the run method of this thread.
The start() method causes this thread to begin execution; the Java Virtual
Machine calls the run method of this thread. This method cannot pause execution of a thread.
Further, the threads are inherently deadlock-prone.
Which of the following is not platform independent in Java?
a. Everything in Java thread is platform dependent.b. The thread constructor with the stackSize parameter is platform dependent.
c. The inheritance in java is platform dependent as multiple classes are involved.
d. There is no platform dependency in Java.
Answer
b. The thread constructor with the stackSize parameter is platform dependent.
Explanation:
public Thread(ThreadGroup group, Runnable target, String name, long stackSize)
The above constructor allocates a new Thread object so that it has target as its run object, has the
specified name as its name, and belongs to the thread group referred to by group, and has the
specified stack size. This constructor is identical to Thread(ThreadGroup,Runnable,String) with
the exception of the fact that it allows the thread stack size to be specified. The stack size is the
approximate number of bytes of address space that the virtual machine is to allocate for this
thread's stack. The effect of the stackSize parameter, if any, is highly platform dependent. On some
platforms, specifying a higher value for the stackSize parameter may allow a thread to achieve
greater recursion depth before throwing a StackOverflowError. Similarly, specifying a lower value
may allow a greater number of threads to exist concurrently without throwing an
OutOfMemoryError (or other internal error). The details of the relationship between the value of
the stackSize parameter and the maximum recursion depth and concurrency level are platform-
dependent. On some platforms, the value of the stackSize parameter may have no effect
whatsoever.
Due to the platform-dependent nature of the behavior of this constructor, extreme care should be
exercised in its use. The thread stack size necessary to perform a given computation will likely
vary from one JRE implementation to another. In light of this variation, careful tuning of the stack
size parameter may be required, and the tuning may need to be repeated for each JRE
implementation on which an application is to run.
The following is a simple program using the concept of thread.
public class Question extends Thread{
public void run(){
for(int i=1;i<5;i++){
System.out.println(++i);
}
}
public static void main(String args[]){
Question t1=new Question();
t1.run();
}
}What is the output of the above program?
a. a. 1 3b. 2 4
6
8
c. Runtime error
d. 2 4
Answer
b. 2
4
6
8
The increment operators increase the value of i to 2 in the first run. Afterwards, two increments
are happening till i > 8 condition is not satisfied.
For the program given below, what will be the output after its execution?
public class Main{
public static void main(String[]args){
Thread thread=Thread.currentThread();
thread.run();
System.out.print(thread.activeCount());
}
}b. 10
c. 01
d. 11
Answer
a. 1
java.lang.Thread.activeCount() : Returns an estimate of the number of active threads in the current thread’s
thread group and its subgroups.
Which of the following method returns a reference to the currently executing thread object?
a. public static boolean interrupted()b. public static Thread currentThread()
c. public final boolean isAlive()
d. public final void suspend()
Answer
b. public static Thread currentThread()
Detailed Solution:
Only public static Thread currentThread() method returns a reference to the currently executing
thread object among the options.
Which of the following methods can be used to reduce over-utilization of CPU?
a. public static void yield()b. public static void main(String args[])
c. public static void sleep(long millis)
d. public void start()
Answer
a. public static void yield()
Explanation:
public static void yield() gives a hint to the scheduler that the current thread is willing to yield its
current use of a processor. The scheduler is free to ignore this hint.
Yield is a heuristic attempt to improve relative progression between threads that would otherwise
over-utilise a CPU. Its use should be combined with detailed profiling and benchmarking to ensure
that it actually has the desired effect.
It is rarely appropriate to use this method. It may be useful for debugging or testing purposes,
where it may help to reproduce bugs due to race conditions. It may also be useful when designing
concurrency control constructs such as the ones in the java.util.concurrent.locks package.
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