The difference between an empty string ("") and Null

1. Type
Null represents the value of an object, not a string. For example, declaring a reference to an object, String a = null;
"" represents an empty string, meaning that it is 0 in length. For example, declare a string str = "";

2. Memory allocation
String str = NULL; Represents a reference that declares a string object, but points to null, which means that no memory space has been pointed to;
String str = ""; Represents a reference to a string type, with a value of "" an empty string, which refers to the memory space of an empty string;

In Java, variables and reference variables are present in the stack (stack), and objects (new) are stored in the heap (heap):

The difference between an empty string ("") and Null