All objects are refered to with a reference. So when you declare
String str = "Hello, World!";
This is a reference named str that refers to a String object. In Java, you never manipulate objects directly. However, I don't think it's possible to get the phyiscal address and manipulate it. In fact, the lack of pointer arithmetic is one of the purported strengths of Java. Can you explain what prompted this question? What are you trying to do exactly? Hopefully we can give some more detailed advice if you provide a clear explanation.
Actually i want difference between String str="vas"; String str1= new String("vas");
I came to known first Statement creates only one reference that is pointed out by str; but for the second statement I find that String Literal vas is referenced by something and that something is referenced by str1;