What is a String Builder in java

Answer 1

Pretty sure the answer has something to do with multi threading..

jk.

it's a dynamic array that can produce equivalent strings on demand.

Answer 2

StringBuilder is Java class that is usually used as substitution for String class when you need to do a lot of concatenation, for example:

String a = "";

for(int i = 0; i < 100; i++){
a += "a"
}

So, since String class is IMMUTABLE and you cannot change its value, what is really happening is that in every iteration compiler makes completely NEW OBJECT of String class and assigns a value of the old string and new value to it concatenated.

StringBuilder is mutable, so there is no making new objects when assigning new values while iterating.

So, you should use StringBuilder when you are certain that value of your string CHANGES A LOT.

You can always transfer your StringBuilder object to string with simple .toString() method when finished.

Answer 3

@Prakhar Agarwal
Good question.

From java docs (StringBuffer):

As of release JDK 5, this class has been supplemented with an equivalent class designed for use by a single thread, StringBuilder. The StringBuilder class should generally be used in preference to this one, as it supports all of the same operations but it is faster, as it performs no synchronization.

So, you should use StringBuilder over StringBuffer if you don't do multithreading.

Answer 4

string: immutable
stringBuffer:mutable nd Unsynchronized
stringBuildr:Mutable and Synchronized (such that use in multithreaded environment)

Answer 5

Thnx Leon
But can u send me any example of it

Answer 6

Thnx for ur help

Answer 7

Thnx Milunovic but is it same. as string buffer