The difference between String,stringbuffer and StringBuilder

1. Definition:

String: String class represents strings.

All string literals (such as) in a Java program "abc" are implemented as instances of this class.

Strings are constants, and their values cannot be changed after they are created.

A string buffer supports variable strings.

Because the String object is immutable. So to be able to share. Like what:

String str = "abc"; equivalent to char data[] = {' A ', ' B ', ' C '}; string str = new string (data);

StringBuffer: String The string buffer. But cannot be changed. Although it includes a specific sequence of characters at random points in time, some method calls can change the length and content of the sequence.
    appendinsertMethod. These methods can be overloaded to accept arbitrary types of data. Each method effectively converts the given data to a string. The character of the string is then appended or inserted into the string buffer. append insert Method adds a character to the specified point.
    String buffers can be safely used with multiple threads. Be able to synchronize these methods when necessary. As a result, all operations on a particular instance appear to occur in a serial order that is consistent with the sequence of method calls made by each thread involved.
StringBuilder:A variable sequence of characters. This class provides aStringBuffercompatible APIs, but does not guarantee synchronization. This class is designed to be used asStringBufferA simple replacement for a string buffer that is used by a single thread (this is a very common situation).
If possible, it is recommended that the class be preferred, since in most implementations it is moreStringBufferbe quick.   Span style= "FONT-FAMILY:ARIAL,HELVETICA,SANS-SERIF; Font-weight:normal "> Main operation is   Append   and  insert   method. These methods can be overloaded to accept arbitrary types of data. Each method effectively converts the given data to a string. The character of the string is then appended or inserted into the string generator.  append   method always adds these characters to the end of the generator, while the  insert   Method adds a character to the specified point. 
2. Differences:
Comparison of operating speed: StringBuilder >  stringbuffer.
Suppose you want to manipulate a small amount of data with = String
 single-threaded operation string buffer Large amount of data under operation = StringBuilder   
Multi-threaded operation string buffers operation of large amounts of data = StringBuffer

The difference between String,stringbuffer and StringBuilder