The == operator works on String object references. If two
String variables point to the same object in memory, the
comparison returns a true result. 

The equals method compares the actual char content of two
strings. This method returns true when two String objects
hold char data with the same values.

If string a="aaaa"; and String b="bbbb";
we can compare them as
if(a.equals(b)) and get a boolean as a return type.

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We can also compare String as 
a.compareTo("aaaa"); which gives 0 as output as they are 
equal.

by overriding the compare method of comparator class

we can use a string function...
eg:
strcmp("string1","string2")
it return 0 if string1=string2
it return >0 if string1>string2
it return <0 if string1<string2.
value returned depends on anscii calues of strings...