Question

Consider the following codes:

public class TestThread extends Thread {

    public static void main(String[] args) {

        TestThread thread = new TestThread();

    }

    @Override

    public void run() {

        printMyName();

    }

    private void printMyName() {

        System.out.println("Thread is running");

    }

}

Test Stem / Question	Choices
1: What method should you invoke to start the thread TestThread?	A: start()
	B: run()
	C: No. Thread will run automatically when executed.
	D: TestThread is not a thread.
2: What will happen when you started the thread?	A: “Thread is running” will be printed out.
	B: Will have an compiler error, you cannot access a static method in the thread.
	C: Exception will be thrown.
	D: Thread will be started but the “Thread is running” will not be printed since the run method is not called.
3: How many and what threads is/are running when you successfully run the above code?	A: 2, the main thread and the TestThread.
	B: 1, only the main thread
	C: 1, only the TestThread
	D: No thread is running
4: What method is internally called by when we call the method start()?	A: run()
	B: printMyName()
	C: main()
	D: None
5: Now try to use the method getName() and print it out. What does the console say?	A: Thread-0
	B: The name of the class - TestThread
	C: None since we did not define a name for the thread.
	D: Syntax error, not such method exists.

public class TestThread implements Runnable{

        public static void main(String[] args){

                TestThread t = new TestThread();

        }

        public void run() {

            System.out.println("Running");

        }

}

6: How will you be able to run this thread?	A: by calling the run() method.
	B: By calling the start() method.
	C: This will not run since this is a runnable. You need to extend the Thread class.
	D: This will not run since there is no @override annotation in the run method.
7: What will happen when you called the t.start() twice?	A: IllegalStateThreadException will occur.
	B: The “Running” text will be printed twice
	C: Nothing.
	D: MulitThreadingException will occur
8: What will happen when you called t.run() and t.start()?	A: The “Running” text will be printed twice
	B: IllegalStateThreadException will occur.
	C: Nothing.
	D: MulitThreadingException will occur

public class TestExample extends Thread{

      public static void main(String argv[]){

            TestExample t = new TestExample();

            t.run();

      }

      public void start(){

            for(int i = 0; i < 5; i++){

                  System.out.println("Count : " + i);

            }

      }

}

9: What happens when you compile?	A: Nothing but it compiled.
	B: Syntax error. run() method is not defined.
	C: Compiler error.
	D: A run time exception that says no run method is defined in this class.

public class TestExample implements Runnable{

      public static void main(String[] args) throws InterruptedException{

            Thread a = new Thread(new TestExample());

            a.start();

       

            System.out.println("Starting...");

            a.join();

            System.out.println("Ending...");

      }

   

      public void run(){

            System.out.println("Running...");

      }

}

10: What happens when you compile?	A: Starting… Running… Ending… is printed
	B: Starting… Ending… Running… is printed
	C: Starting… Ending… is printed
	D: Runtime exception occurred.

Answer 1

1)

start() method must be invoked to start the thread TestThread

public class TestThread extends Thread {
public TestThread()
{
start();
}
public static void main(String[] args) {
TestThread thread = new TestThread();
}
@Override
public void run() {
printMyName();
}
private void printMyName() {
System.out.println("Thread is running");
}
}

2)

a) Thread is running will be printed on the screen

3)

When thread is started 2 threads will be running i..e, Main thread & TestThread

4)

run() is internally called when the start() method is called

5)

Thread-0 will be printed on the screen

public class TestThread extends Thread {
public TestThread()
{
start();
}
public static void main(String[] args) {
TestThread thread = new TestThread();
}
@Override
public void run() {
printMyName();
}
private void printMyName() {
System.out.println(getName()+"Thread is running");
}
}

Output

Thread-0Thread is running

6)

b is correct option it can be accomplished with the below example

public class TestThread implements Runnable{
public TestThread()
{
new Thread(this).start();
}
public static void main(String[] args){
TestThread t = new TestThread();
}
public void run() {
System.out.println("Running");
}
}

Output

Running

7)

When starting thread twice IllegalThreadStateException will be thrown

8)

a is correct answer

9)

a is correct answer since it doesnot raise any compile time error

10)

a is correct answer since join() method waits for the current thread to finish its execution