Java Programming MCQs - Threads

11. Which of the following line of code is suitable to start a thread ?

  
class X implements Runnable
{
	public static void main(String args[])
	{
	/* Missing code? */
	}
	public void run() {}
}

A. Thread t = new Thread(X);
B. Thread t = new Thread(X); t.start();
C. X run = new X(); Thread t = new Thread(run); t.start();
D. Thread t = new Thread(); x.run();

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12. What will be the output of the program?

class multithreaded_programing
{
	public static void main(String args[])
	{
		Thread t = Thread.currentThread();
		t.setName("New Thread");
		System.out.println(t);
	}
}

A. Thread[5,main].
B. Thread[New Thread,5].
C. Thread[main,5,main].
D. Thread[New Thread,5,main]

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13. Number of threads in below java program is:

public class ThreadExtended extends Thread {
	public void run() {
		System.out.println("Thread is running no");
	}
	public static void main(String[] args) 
	{
		ThreadExtended threadE = new ThreadExtended();
		threadE.start();
	}
}

A. 0
B. 1
C. 2
D. 3

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14. which of these will create and start this thread?

  
public class MyRunnable implements Runnable
{
	public void run()
	{
		// some code here
	}
}

A. new Runnable(MyRunnable).start();
B. new Thread(MyRunnable).run();
C. new Thread(new MyRunnable()).start();
D. new MyRunnable().start();

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15. What is the priority of the thread in output of this program?

class multithreaded_programing
{
	public static void main(String args[])
	{
		Thread t = Thread.currentThread();
		t.setName("New Thread");
		System.out.println(t.getName());
	}
}

A. main
B. Thread
C. New Thread
D. Thread[New Thread,5,main].

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16. What will be the output of the program?

class MyThread extends Thread
{
	public static void main(String [] args)
	{
		MyThread t = new MyThread();
		t.start();
		System.out.print("one. ");
		t.start();
		System.out.print("two. ");
	}
	public void run()
	{
		System.out.print("Thread ");
	}
}

A. Compilation fails
B. An exception occurs at runtime.
C. It prints "Thread one. Thread two."
D. The output cannot be determined.

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17. What is the name of the thread in output of this program?

  
class multithreaded_programing
{
	public static void main(String args[])
	{
		Thread t = Thread.currentThread();
		System.out.println(t.getPriority());
	}
}

A. 1
B. 4
C. 0
D. 5

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18. What is the name of the thread in output of this program?

  
class multithreaded_programing
{
	public static void main(String args[])
	{
		Thread t = Thread.currentThread();
		System.out.println(t.isAlive());
	}
}

A. 1
B. 0
C. TRUE
D. FALSE

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19. The following block of code creates a Thread using a Runnable target:Which of the following classes can be used to create the target, so that the preceding code compiles correctly?

  
Runnable target = new MyRunnable();
Thread myThread = new Thread(target);

A. public class MyRunnable extends Object{public void run(){}}
B. public class MyRunnable implements Runnable{void run(){}}
C. public class MyRunnable implements Runnable{public void run(){}}
D. public class MyRunnable extends Runnable{public void run(){}}

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20. The static method Thread.currentThread() returns a reference to the currently executing Thread object. What is the result of this code?

  	  
class Test
{
	public static void main(String [] args)
	{
		printAll(args);
	}
	public static void printAll(String[] lines)
	{
		for(int i = 0; i < lines.length; i++)
		{
			System.out.println(lines[i]);
			Thread.currentThread().sleep(1000);
		}
	}
}

A. Each String in the array lines will output, and there is no guarantee there will be a pause because currentThread() may not retrieve this thread.
B. Each String in the array lines will output, with no pause in between because this method is not executed in a Thread.
C. Each String in the array lines will output, with a 1-second pause.
D. This code will not compile.

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