Java thread MCQ - Quiz

Analyze the following code: 
public class Test implements Runnable{
        public static void main(String[] args){
                Test t = new Test();
                t.start();
        }

        public void run() { }
}

  • A The program does not compile because the start() method is not defined in the Test class.
  • B The program compiles, but it does not run because the start() method is not defined.
  • C The program compiles, but it does not run because the run() method is not implemented.
  • D The program compiles and runs fine.

What will happen after compiling and running following code? 
class A implements Runnable{
      public void run(){
            System.out.println("run-a");
      }
}

1. public class Test{
2.       public static void main(String... args){
3.             A a = new A();
4.             Thread t = new Thread(a);
5.             t.start();
6.             t.start();
7.       }
8. }

  • A run-a
  • B run-a run-a
  • C Compilation fails with an error at line 6
  • D Compilation succeed but Runtime Exception

Which of the following are methods of the Thread class?

1) yield()
2) sleep(long msec)
3) go()
4) stop()
  • A 1 , 2 and 4
  • B 1 and 3
  • C 3 only
  • D None of the above

Predict the output: 
class A implements Runnable{
      public void run(){
            try{
                  for(int i=0;i<4;i++){
                        Thread.sleep(100);
                        System.out.println(Thread.currentThread().getName());
                  }
            }catch(InterruptedException e){
            }
      }
}

public class Test{
      public static void main(String argv[]) throws Exception{
            A a = new A();
            Thread t = new Thread(a, "A");
            Thread t1 = new Thread(a, "B");
            t.start();
            t.join();
            t1.start();
      }
}

  • A A A A A B B B B
  • B A B A B A B A B
  • C Output order is not guaranteed
  • D Compilation succeed but Runtime Exception

In java, a thread can be created by ..........
  • A Extending the thread class.
  • B Implementing Runnable interface.
  • C Both of the above
  • D None of these

What will be the output? 
class One extends Thread{
	public void run(){
		for(int i=0; i<2; i++){
			System.out.print(i);
		}
	}
}

public class Test{
	public static void main(String args[]){
		Test t = new Test();
		t.call(new One());
	}
	
	public void call(One o){
		o.start();
	}
}

  • A 0 0
  • B Compilation Error
  • C 0 1
  • D None of these

When a class extends the Thread class, it should override ............ method of Thread class to start that thread.
  • A start()
  • B run()
  • C init()
  • D go()

What will be the output of the following program code? 
public class Test implements Runnable{
        public static void main(String[] args){
                Thread t = new Thread(this);
                t.start();
        }

        public void run(){
                System.out.println("test");
        }
}

  • A The program does not compile because this cannot be referenced in a static method.
  • B The program compiles fine, but it does not print anything because t does not invoke the run() method
  • C The program compiles and runs fine and displays test on the console.
  • D None of the above

What will happen when you attempt to compile and run the following code? 
class A implements Runnable{
      public void run(){
            System.out.println("run-A");
      }
}

1. public class Test{
2.       public static void main(String argv[]){
3.             A a = new A();
4.             Thread t = new Thread(a);
5.             System.out.println(t.isAlive());
6.             t.start();
7.             System.out.println(t.isAlive());
8.       }
9. }

  • A false run-A true
  • B false run-A false
  • C true run-A true
  • D Compilation fails due to an error on line 7