The difference between string, StringBuffer, StringBuilder in Java

String, StringBuffer, and StringBuilder are common string classes in Java , so let's look at the similarities and differences between the three.

One, variable and immutable:

String: Constant, immutable. StringBuffer, StringBuilder are variable character sequences, and are variable.

Second, whether multithreading security:

The objects in string are immutable, equal to constants, and apparently thread-safe .

StringBuffer: multithreading security is supported.

StringBuilder: multithreading security is not supported .

　　

Iii. efficiency of implementation:

String, StringBuffer, StringBuilder are used for concatenation of strings: string str1= "ASDFGH"; String str2= "LKJHDSA";

Method One,

Use string:string str3=str1+str2; lowest efficiency .

Method Two,

Use Stringbuffer::str1.append (STR2);　　Append using Stringbuiffer's Append () method. High Efficiency (because of its need to achieve thread safety, it is less efficient than StringBuilder. ）

Method Three,

Use StringBuilder:str1.append (STR2);　　Append using StringBuilder's Append () method. most efficient . (No thread safety issues, so execution is the most efficient)

Summarize:

First, if you want to manipulate a small amount of data, with a string, single-threaded operation of large amounts of data, with StringBuilder, multi-threaded operation of a large number of data, with StringBuffer.

Second, do not use the String class "+" for frequent splicing , because that performance is very poor, you should use the StringBuffer or StringBuilder class.

　 Note:Both StringBuilder and StringBuffer have the following methods to display the stringincrease, delete, change, checkFunction.

Add: Insert ();

Deletion: Delete ();

Change: replace ();

Check: IndexOf ();

For specific usage, refer to the Java API documentation.

The difference between string, StringBuffer, StringBuilder in Java