String, StringBuilder, stringbuffer differences in Java

1. Variable and non-changeable

The string class uses a character array to hold strings, as follows, because there is a "final" modifier, so you know that the string object is immutable. Each time a change is made to a string object, it is equivalent to generating a new string object and then pointing the reference to the new string object, the original string object GC is recycled.

Private final char value[];

Both Stringbuider and StringBuffer inherit from the Abstractstringbuider class, and in the Abstractstringbuilder, they are also used to hold strings in a character array, as follows, that both of these objects are mutable.

Char[] value;

2. Whether multithreaded security

The objects in string are immutable and can be understood as constants, apparently thread-safe.

Abstractstringbuilder is the common parent class of Stringbuider and StringBuffer, which defines some basic operations of strings. such as expandcapacity, append, insert, indexof and other public methods.

StringBuffer is thread-safe because it adds a synchronous lock to a method or to a method called. Source:

 Public synchronized StringBuffer reverse () {        super.reverse ();         return  This ;}  Public int indexOf (String str) {    return0);   }

StringBuilder does not have a synchronous lock on the method, so it is non-thread safe.

StringBuffer is suitable for multi-threaded programs, ensuring synchronization. The StringBuilder is suitable for single-threaded programs and does not guarantee synchronization.

In most cases StringBuilder > StringBuffer > String, it is recommended to use the StringBuilder class.

String, StringBuilder, stringbuffer differences in Java