what is difference between length() and length

Answer 1

length is a property which gives length of an array. On the other hand, length() is a method that returns length of a String (In Java, Strings are not considered as character arrays)

Answer 2

in the array class there's a variable named length, there's also a function named getLength ();
for other Objects, there a function named length ()

Answer 3

There is no difference :)