Initialization of the Java string type

The following is basically the three most common method of Java string Type new string () does not describe the basic equivalent of the third

String A; Declares a string type A, which does not have a memory address in the request, nor any point in memory to the reference address;

String a = null; Declare a string of type A, while in memory requested an address, but the address does not point to any reference address;

String a = ""; Declare a string of type A, both in the memory of the application of the address, which also points to a reference to the string reference address;

It is generally best to use string a = "";
You can prevent subsequent programs from being unable to find an exception because of a confusing reference address!
String a = null;  String A;  Try to use less! No need to use it!

Initialization of the Java string type