Difference between String; String Builder; and String Buffer

String: String variables are stored in “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 retains 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 same as String Buffer except for the String Builder which is not threaded safety that is not synchronized. So obviously performance is fast.