Exceptions

Throw is used for throwing exceptions explicitly. Let's say in your program you don't want to allow some values or conditions. As these values are might not be exceptions but you want to throw an exception. For these situations throw comes. You can use throw to throw any kind of exception even without its occurrence. 

Syntax:throw exception_name_to_throw;

Throws is use for providing the security to calee function. If we use throws with any function then it means that function can not be called until calee makes proper arrangement of handling the exception thrown by the function to call. 

Snatax: function_name() throws Exception_name {
     ...rest of the function code...
 }

It is mandatory to catch exception thrown by Throw and Throws.   

Example:

class test extends Exception{
public static void main(String args[]) throws Exception{
//demo of throw
int x=0;
throw new Exception("Throw demo"); //Comment this line for throws demo and uncomment the throws demo section
//Throws demo
// try{
// useThrows(); // this call is possible only from try block.
// }catch(Exception e){
// System.out.println(e.toString());
// }

}
static void useThrows() throws Exception{
//it is mandatory to call me from try and catch block only.
int x= 5/0;

}
}

Live Demo:

http://ideone.com/DHhjVx