There are two ways of creating a thread; extend (sub-class) the Thread class and implement the Runnable interface. For both of these ways you must implement (override and not overload) 

the public void run() method.

(1) is correct - Extending the Thread class and overriding its run method is a valid procedure.

(4) is correct - You must implement interfaces, and runnable is an interface and you must also

 include the run method.

(2) is wrong - Runnable is an interface which implements not Extends. Gives the error: (No 

interface expected here)

(3) is wrong - You cannot implement java.lang.Thread (This is a Class). (Implements Thread, 

gives the error: Interface expected). Implements expects an interface.

(5) is wrong - You cannot implement java.lang.Thread (This is a class). You Extend classes, 

and Implement interfaces. (Implements Thread, gives the error: Interface expected)