String: String variables are stored in a “constant string pool”. Once the string reference changes the old value that exists in the “constant string pool”, it cannot be erased.
Example:
String name = “book”;
Constant string pool
If the name-value has changed from “book” to “pen”.
Constant string pool
Then the older value remains in the constant string pool.
String Buffer:
Here string values are stored in a stack. If the values are changed then the new value replaces the older value.
The string buffer is synchronized which is thread-safe.
Performance is slower than the String Builder.
Example:
String Buffer name =”book”;
Once the name value has been changed to “pen” then the “book” is erased in the stack.
String Builder:
This is the same as String Buffer except for the String Builder which is not threaded safely that is not synchronized. So obviously the performance is fast.
