字符串-Java中的堆栈和堆

Question

I know that Strings are stored on the heap and the reference to them is stored on the stack. So in the code below one would point to "John" on the heap from the stack and likewise two would point to "Smith" on the heap from the stack.

So what happens when i do one = two ? Does one now point to where two points to because two contains a reference to a point on the heap or does it change the "John" on the heap to "Smith" ?

String one;
one = "John";
String two = "Smith"
one = two;

Answer 1

In your example, one now points to the same place as two . The original string on the heap "John" becomes garbage and is subject to garbage collection.

It's not possible to see in this example because String is immutable, but if these were mutable data structures such as an ArrayList , then modifying the object through one would make the same change visible through two , because they point to the same object.

Answer 2

Now one will point to the two .
Since all string are immutable then when they are created then they are stored in heap and referenced by variable but when you make or assign new variable to same string then it will not explicitly create new string but just reference to same string which is in heap

from above picture you can easily understand the concept of immutability.
for reference Where does java reference variable stored?