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() {} 
}

(1), (2), and (6) are correct. They are all related to the list of threads waiting on the specified object.

(3), (5), (7), and (8) are incorrect answers. The methods isInterrupted() and interrupt() are instance methods of Thread.

The methods sleep() and yield() are static methods of Thread.

D is incorrect because synchronized is a keyword and the synchronized() construct is part of the Java language.

Option A is valid declaration of float.

Option B is incorrect because any literal number with a decimal point u declare the computer will implicitly cast to double unless you include "F or f"

Option C is incorrect because it is a String.

Option D is incorrect because "d" tells the computer it is a double so therefore you are trying to put a double value into a float variable i.e there might be a loss of precision.

Hashtable is the only class listed that provides synchronized methods. If you need synchronization great; otherwise, use HashMap, it's faster.

(2) - This is a Java keyword

(3) - This is a Java keyword

(1) - Is incorrect because although it is a method of Thread/Runnable it is not a keyword

(4) - This is not a Java keyword the keyword is implements

An object that maps keys to values. A map cannot contain duplicate keys; each key can map to at most one value.

(2) is correct because wait() always causes the current thread to go into the object's wait pool.

(5) is correct because sleep() will always pause the currently running thread for at least the duration specified in the sleep argument (unless an interrupted exception is thrown).

(6) is correct because, assuming that the thread you're calling join() on is alive, the thread calling join() will immediately block until the thread you're calling join() on is no longer alive.

(1) is wrong, but tempting. The yield() method is not guaranteed to cause a thread to leave the running state, although if there are runnable threads of the same priority as the currently running thread, then the current thread will probably leave the running state.

(3) and (4) are incorrect because they don't cause the thread invoking them to leave the running state.

(7) is wrong because there's no such method.

(1) and (2) are both valid constructors for Thread.

(3), (4), and (5) are not legal Thread constructors, although (4) is close. If you reverse the arguments in (4), you'd have a valid constructor.

Option C is correct. notify() - wakes up a single thread that is waiting on this object's monitor.

(1) and (4). Only start() and run() are defined by the Thread class.

(2) and (3) are incorrect because they are methods of the Object class. (5) is incorrect because there's no such method in any thread-related class.

Option C is correct. The start() method causes this thread to begin execution; the Java Virtual Machine calls the run method of this thread.

Option A is wrong. The run() method of a thread is like the main() method to an application. Starting the thread causes the object's run method to be called in that separately executing thread.

Option B is wrong. There is no construct() method in the Thread class.

Option D is wrong. There is no register() method in the Thread class.